Reverse transcriptase-like; This domain is found in plants and appears to be part of a retrotransposon.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15238647   155 DENGKGKMTDVVSGFGVAICDQRDNLLFEMKGPLiDNGMSRQGAELKALIRGLTEALKLGIKHIVFFCDSYPIFQYVTGK 234
Cdd:pfam13456   1 NFDGAFKCDSGLAGAGVVIRDPNGNVLLAGQKKL-GPGASVLEAEAQALIIGLQLAWKLGIRHLIVEGDSATVVQLINGR 79

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 15238647   235 WMaKQKKISLLLDDLQSIMQHFSSYQHVLVARNDVKFAYKLARES 279
Cdd:pfam13456  80 SP-KQSKLANLLDEIRKLLKRFESVSFEHIPREQNRVADTLAKMA 123

Rcat domain found in an uncharacterized subfamily of RBR proteins; This subfamily contains uncharacterized members of the RBR family, including Arabidopsis thaliana mutator-like transposase and hypothetical protein At2g19610/F3P11.21. The RBR family of RING-type E3 ligases are characterized by containing a RBR domain, which was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. It is composed of an extended RING domain (RING1) followed by an in-between RING (IBR) domain and the catalytic domain, which is structurally an IBR domain but is commonly designated RING2. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently, where the IBR and RING2 domains have been renamed as BRcat and Rcat domains, respectively. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. RBR family members play roles in protein quality control and can indirectly regulate transcription. Evidence suggests that RBR proteins are often parts of cullin-containing ubiquitin ligase complexes. This model corresponds to the Rcat domain that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 15238647 466 MWRQCGKCQHMIELSQGCNHITCRCGHEFCYNCGGGW 502
Cdd:cd22584   1 GWRRCPQCGHMVELSEGCNHMTCRCGYEFCYLCGAPW 37

Reverse transcriptase-like; This domain is found in plants and appears to be part of a retrotransposon.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15238647   155 DENGKGKMTDVVSGFGVAICDQRDNLLFEMKGPLiDNGMSRQGAELKALIRGLTEALKLGIKHIVFFCDSYPIFQYVTGK 234
Cdd:pfam13456   1 NFDGAFKCDSGLAGAGVVIRDPNGNVLLAGQKKL-GPGASVLEAEAQALIIGLQLAWKLGIRHLIVEGDSATVVQLINGR 79

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 15238647   235 WMaKQKKISLLLDDLQSIMQHFSSYQHVLVARNDVKFAYKLARES 279
Cdd:pfam13456  80 SP-KQSKLANLLDEIRKLLKRFESVSFEHIPREQNRVADTLAKMA 123

Rcat domain found in an uncharacterized subfamily of RBR proteins; This subfamily contains uncharacterized members of the RBR family, including Arabidopsis thaliana mutator-like transposase and hypothetical protein At2g19610/F3P11.21. The RBR family of RING-type E3 ligases are characterized by containing a RBR domain, which was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. It is composed of an extended RING domain (RING1) followed by an in-between RING (IBR) domain and the catalytic domain, which is structurally an IBR domain but is commonly designated RING2. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently, where the IBR and RING2 domains have been renamed as BRcat and Rcat domains, respectively. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. RBR family members play roles in protein quality control and can indirectly regulate transcription. Evidence suggests that RBR proteins are often parts of cullin-containing ubiquitin ligase complexes. This model corresponds to the Rcat domain that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 15238647 466 MWRQCGKCQHMIELSQGCNHITCRCGHEFCYNCGGGW 502
Cdd:cd22584   1 GWRRCPQCGHMVELSEGCNHMTCRCGYEFCYLCGAPW 37

RNAse HI family that includes archaeal, some bacterial as well as plant RNase HI; Ribonuclease H (RNase H) is classified into two evolutionarily unrelated families, type 1 (prokaryotic RNase HI, eukaryotic RNase H1 and viral RNase H) and type 2 (prokaryotic RNase HII and HIII, and eukaryotic RNase H2). RNase H is an endonuclease that cleaves the RNA strand of an RNA/DNA hybrid in a sequence non-specific manner. RNase H is involved in DNA replication, repair and transcription. RNase H is widely present in various organisms, including bacteria, archaea and eukaryotes and most prokaryotic and eukaryotic genomes contain multiple RNase H genes. Despite the lack of amino acid sequence homology, type 1 and type 2 RNase H share a main-chain fold and steric configurations of the four acidic active-site (DEDD) residues and have the same catalytic mechanism and functions in cells. One of the important functions of RNase H is to remove Okazaki fragments during DNA replication. Most archaeal genomes contain only type 2 RNase H (RNase HII); however, a few contain RNase HI as well. Although archaeal RNase HI sequences conserve the DEDD active-site motif, they lack other common features important for catalytic function, such as the basic protrusion region. Archaeal RNase HI homologs are more closely related to retroviral RNase HI than bacterial and eukaryotic type I RNase H in enzymatic properties.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15238647 145 YRLYFKGLvSDENGKGkmtdvvSGFGVAICDQrDNLLFEMKGPL---IDNGMsrqgAELKALIRGLTEALKLGIKHIVFF 221
Cdd:cd09279   1 WTLYFDGA-SRGNPGP------AGAGVVIYSP-GGEVLELSERLgfpATNNE----AEYEALIAGLELALELGAEKLEIY 68

                        90       100       110       120       130
                ....*....|....*....|....*....|....*....|....*....|....*....
gi 15238647 222 CDSYPIFQYVTGKWMAKQKKISLLLDDLQSIMQHFSSYQHVLVARNDVKFAYKLARESI 280
Cdd:cd09279  69 GDSQLVVNQLNGEYKVKNERLKPLLEKVLELLAKFELVELKWIPREQNKEADALANQAL 127

RING finger, HC subclass, found in two RING fingers and DRIL [double RING finger linked] 1 (TRIAD1); TRIAD1, also known as ariadne-2 (ARI-2), protein ariadne-2 homolog, Ariadne RBR E3 ubiquitin protein ligase 2 (ARIH2), or UbcM4-interacting protein 48, is an RBR-type E3 ubiquitin-protein ligase that catalyzes the formation of polyubiquitin chains linked via lysine-48, as well as lysine-63 residues. Its auto-ubiquitylation can be catalyzed by the E2 conjugating enzyme UBCH7. TRIAD1 has been implicated in hematopoiesis, specifically in myelopoiesis, as well as in embryogenesis. It functions as a regulator of endosomal transport and is required for the proper function of multivesicular bodies. It also acts as a novel ubiquitination target for proteasome-dependent degradation by murine double minute 2 (MDM2). As a proapoptotic protein, TRIAD1 promotes p53 activation, and inhibits MDM2-mediated p53 ubiquitination and degradation. Furthermore, TRIAD1 can inhibit the ubiquitination and proteasomal degradation of growth factor independence 1 (Gfi1), a transcriptional repressor essential for the function and development of many different hematopoietic lineages. TRIAD1 contains an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR (RING1-BRcat-Rcat) domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase function to facilitate the ubiquitination reaction. This model corresponds to the RING domain, a C3HC4-type RING-HC finger required for RBR-mediated ubiquitination.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....
gi 15238647 300 ECAICFNDIVAEGMFSVDkCRHRFCFQCVKQHVEVKLLHGMAP--KCPHDGCKS 351
Cdd:cd16773   2 TCGVCCEDVPKDELFSLA-CGHYFCNDCWKQYLTVKIKDGVSTgiECMAPDCKV 54

IBR domain, a half RING-finger domain; The IBR (In Between Ring fingers) domain is often found to occur between pairs of ring fingers (pfam00097). This domain has also been called the C6HC domain and DRIL (for double RING finger linked) domain. Proteins that contain two Ring fingers and an IBR domain (these proteins are also termed RBR family proteins) are thought to exist in all eukaryotic organizms. RBR family members play roles in protein quality control and can indirectly regulate transcription. Evidence suggests that RBR proteins are often parts of cullin-containing ubiquitin ligase complexes. The ubiquitin ligase Parkin is an RBR family protein whose mutations are involved in forms of familial Parkinson's disease.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|
gi 15238647   459 KSLANNKMWRQC--GKCQHMIELSQGCN---HITC-RCGHEFCYNCGGGW 502
Cdd:pfam01485  10 SYVESDPNLKWCptPDCGYIIELTDGCSntsHVTCsKCGHEFCFNCKEEW 59

Ring finger domain;

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*..
gi 15238647   300 ECAICFNDIVAEGMFSVDKCRHRFCFQCVKQHVEvkllhgMAPKCPH 346
Cdd:pfam13639   2 ECPICLEEFEEGDKVVVLPCGHHFHRECLDKWLR------SSNTCPL 42

Reverse transcriptase-like; This domain is found in plants and appears to be part of a retrotransposon.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15238647   155 DENGKGKMTDVVSGFGVAICDQRDNLLFEMKGPLiDNGMSRQGAELKALIRGLTEALKLGIKHIVFFCDSYPIFQYVTGK 234
Cdd:pfam13456   1 NFDGAFKCDSGLAGAGVVIRDPNGNVLLAGQKKL-GPGASVLEAEAQALIIGLQLAWKLGIRHLIVEGDSATVVQLINGR 79

                          90       100       110       120
                  ....*....|....*....|....*....|....*....|....*
gi 15238647   235 WMaKQKKISLLLDDLQSIMQHFSSYQHVLVARNDVKFAYKLARES 279
Cdd:pfam13456  80 SP-KQSKLANLLDEIRKLLKRFESVSFEHIPREQNRVADTLAKMA 123

Rcat domain found in an uncharacterized subfamily of RBR proteins; This subfamily contains uncharacterized members of the RBR family, including Arabidopsis thaliana mutator-like transposase and hypothetical protein At2g19610/F3P11.21. The RBR family of RING-type E3 ligases are characterized by containing a RBR domain, which was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. It is composed of an extended RING domain (RING1) followed by an in-between RING (IBR) domain and the catalytic domain, which is structurally an IBR domain but is commonly designated RING2. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently, where the IBR and RING2 domains have been renamed as BRcat and Rcat domains, respectively. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. RBR family members play roles in protein quality control and can indirectly regulate transcription. Evidence suggests that RBR proteins are often parts of cullin-containing ubiquitin ligase complexes. This model corresponds to the Rcat domain that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 15238647 466 MWRQCGKCQHMIELSQGCNHITCRCGHEFCYNCGGGW 502
Cdd:cd22584   1 GWRRCPQCGHMVELSEGCNHMTCRCGYEFCYLCGAPW 37

RNAse HI family that includes archaeal, some bacterial as well as plant RNase HI; Ribonuclease H (RNase H) is classified into two evolutionarily unrelated families, type 1 (prokaryotic RNase HI, eukaryotic RNase H1 and viral RNase H) and type 2 (prokaryotic RNase HII and HIII, and eukaryotic RNase H2). RNase H is an endonuclease that cleaves the RNA strand of an RNA/DNA hybrid in a sequence non-specific manner. RNase H is involved in DNA replication, repair and transcription. RNase H is widely present in various organisms, including bacteria, archaea and eukaryotes and most prokaryotic and eukaryotic genomes contain multiple RNase H genes. Despite the lack of amino acid sequence homology, type 1 and type 2 RNase H share a main-chain fold and steric configurations of the four acidic active-site (DEDD) residues and have the same catalytic mechanism and functions in cells. One of the important functions of RNase H is to remove Okazaki fragments during DNA replication. Most archaeal genomes contain only type 2 RNase H (RNase HII); however, a few contain RNase HI as well. Although archaeal RNase HI sequences conserve the DEDD active-site motif, they lack other common features important for catalytic function, such as the basic protrusion region. Archaeal RNase HI homologs are more closely related to retroviral RNase HI than bacterial and eukaryotic type I RNase H in enzymatic properties.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15238647 145 YRLYFKGLvSDENGKGkmtdvvSGFGVAICDQrDNLLFEMKGPL---IDNGMsrqgAELKALIRGLTEALKLGIKHIVFF 221
Cdd:cd09279   1 WTLYFDGA-SRGNPGP------AGAGVVIYSP-GGEVLELSERLgfpATNNE----AEYEALIAGLELALELGAEKLEIY 68

                        90       100       110       120       130
                ....*....|....*....|....*....|....*....|....*....|....*....
gi 15238647 222 CDSYPIFQYVTGKWMAKQKKISLLLDDLQSIMQHFSSYQHVLVARNDVKFAYKLARESI 280
Cdd:cd09279  69 GDSQLVVNQLNGEYKVKNERLKPLLEKVLELLAKFELVELKWIPREQNKEADALANQAL 127

Rcat domain found in E3 ubiquitin-protein ligase ARI7 and similar proteins; This subfamily contains probable RBR-type E3 ubiquitin-protein ligases (EC 2.3.2.31) including Arabidopsis thaliana ARI5, ARI6, ARI7, and ARI8, as well as Dictyostelium discoideum RbrA (also called Ariadne-like ubiquitin ligase). They may function as part of E3 complexes, which accept ubiquitin from E2 ubiquitin-conjugating enzymes and then transfer it to substrates. RbrA may be required for normal cell-type proportioning and cell sorting during multicellular development, and is also necessary for spore cell viability. Members of this subfamily contain an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of ARI7-like proteins that are essential for RBR E3 ligase activity and adopt the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 15238647 468 RQCGKCQHMIELSQGCNHITCR--CGHEFCYNCGGGW 502
Cdd:cd22583   3 KPCPKCKRPIEKNQGCMHMTCSppCKHEFCWLCLGPW 39

IBR domain, a half RING-finger domain; The IBR (In Between Ring fingers) domain is often found to occur between pairs of ring fingers (pfam00097). This domain has also been called the C6HC domain and DRIL (for double RING finger linked) domain. Proteins that contain two Ring fingers and an IBR domain (these proteins are also termed RBR family proteins) are thought to exist in all eukaryotic organizms. RBR family members play roles in protein quality control and can indirectly regulate transcription. Evidence suggests that RBR proteins are often parts of cullin-containing ubiquitin ligase complexes. The ubiquitin ligase Parkin is an RBR family protein whose mutations are involved in forms of familial Parkinson's disease.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 15238647   368 KLWQQRLQENAIPVT-ERVYCPYPRCSALMSKTKISEsaksllslypKSGVRRCVECRGLFCVDCKVPWHGNLSC 441
Cdd:pfam01485   1 EKYEKLLLKSYVESDpNLKWCPTPDCGYIIELTDGCS----------NTSHVTCSKCGHEFCFNCKEEWHEGLTC 65

RING finger, HC subclass, found in two RING fingers and DRIL [double RING finger linked] 1 (TRIAD1); TRIAD1, also known as ariadne-2 (ARI-2), protein ariadne-2 homolog, Ariadne RBR E3 ubiquitin protein ligase 2 (ARIH2), or UbcM4-interacting protein 48, is an RBR-type E3 ubiquitin-protein ligase that catalyzes the formation of polyubiquitin chains linked via lysine-48, as well as lysine-63 residues. Its auto-ubiquitylation can be catalyzed by the E2 conjugating enzyme UBCH7. TRIAD1 has been implicated in hematopoiesis, specifically in myelopoiesis, as well as in embryogenesis. It functions as a regulator of endosomal transport and is required for the proper function of multivesicular bodies. It also acts as a novel ubiquitination target for proteasome-dependent degradation by murine double minute 2 (MDM2). As a proapoptotic protein, TRIAD1 promotes p53 activation, and inhibits MDM2-mediated p53 ubiquitination and degradation. Furthermore, TRIAD1 can inhibit the ubiquitination and proteasomal degradation of growth factor independence 1 (Gfi1), a transcriptional repressor essential for the function and development of many different hematopoietic lineages. TRIAD1 contains an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR (RING1-BRcat-Rcat) domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase function to facilitate the ubiquitination reaction. This model corresponds to the RING domain, a C3HC4-type RING-HC finger required for RBR-mediated ubiquitination.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....
gi 15238647 300 ECAICFNDIVAEGMFSVDkCRHRFCFQCVKQHVEVKLLHGMAP--KCPHDGCKS 351
Cdd:cd16773   2 TCGVCCEDVPKDELFSLA-CGHYFCNDCWKQYLTVKIKDGVSTgiECMAPDCKV 54

Rcat domain found in E3 ubiquitin-protein ligase ARI1 and similar proteins; This subfamily contains probable RBR-type E3 ubiquitin-protein ligases (EC 2.3.2.31) including Arabidopsis thaliana ARI1, ARI2, and ARI3. They may function as part of E3 complexes, which accept ubiquitin from E2 ubiquitin-conjugating enzymes and then transfer it to substrates. Members of this subfamily contain an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of ARI1-like proteins that are essential for RBR E3 ligase activity and adopt the same fold as the BRcat domain.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....
gi 15238647 470 CGKCQHMIELSQGCNHITCRCGHEFCYNCGGG------WNKIMG 507
Cdd:cd22586   7 CPKCSKPVEKNGGCNLVTCRCGQHFCWLCGAAtgrdhtWESIAG 50

Rcat domain found in RING finger protein 217 (RNF217); RNF217, also called IBR domain-containing protein 1 (IBRDC1), is a transmembrane (TM) domain-containing RBR-type E3 ubiquitin-protein ligase, with different splice variants, that is mainly expressed in testis and skeletal muscle. It interacts with the anti-apoptotic protein HAX1, and is adjacent to a translocation breakpoint involving ETV6 in childhood acute lymphoblastic leukemia (ALL). RNF217 contains an RBR domain followed by TMs. The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of RNF217 that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|...
gi 15238647 469 QCGKCQHMIELSQGCNHITC-RCGHEFCYNCGG 500
Cdd:cd20350   7 KCPKCKVYIQRSEGCDHMTCsQCNTNFCYRCGE 39

Rcat domain found in parkin and similar proteins; Parkin, also called Parkinson juvenile disease protein 2, is an RBR-type E3 ubiquitin-protein ligase that is associated with recessive early onset Parkinson's disease (PD), and exerts a protective effect against dopamine-induced alpha-synuclein-dependent cell toxicity. Mutations in the parkin gene cause autosomal recessive juvenile parkinsonism. Parkin functions within a multiprotein E3 ubiquitin ligase complex, catalyzing the covalent attachment of ubiquitin moieties onto substrate proteins, such as BCL2, SYT11, CCNE1, GPR37, RHOT1/MIRO1, MFN1, MFN2, STUB1, SNCAIP, SEPT5, TOMM20, USP30, ZNF746, and AIMP2. It mediates monoubiquitination as well as Lys6-, Lys11-, Lys48- and Lys63-linked polyubiquitination of substrates depending on the context. Parkin may enhance cell viability and protects dopaminergic neurons from oxidative stress-mediated death by regulating mitochondrial function. It also limits the production of reactive oxygen species (ROS), and regulates cyclin-E during neuronal apoptosis. Moreover, parkin displays a ubiquitin ligase-independent function in transcriptional repression of p53. Parkin contains an N-terminal ubiquitin-like domain and a C-terminal RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of parkin that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 15238647 470 CGKCQHMIELSQGCNHITC---RCGHEFCYNCGGGWN 503
Cdd:cd20357  10 CPKCKVPTEKNGGCMHMKCprpQCGLEWCWICGCEWN 46

Rcat domain found in ankyrin repeat and IBR domain-containing protein 1 (ANKIB1) and similar proteins; ANKIB1 is an RBR-type E3 ubiquitin-protein ligase that may function as part of an E3 complex, which accepts ubiquitin from specific E2 ubiquitin-conjugating enzymes and then transfers it to substrates. It contains N-terminal ankyrin repeats, and an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of ANKIB1 that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|....*.
gi 15238647 470 CGKCQHMIELSQGCNHITCR-CGHEFCYNCGGGWNK 504
Cdd:cd20361  12 CPNCKSPIQKNEGCNHMKCSkCKYDFCWVCLEEWKK 47

In Between Ring fingers; the domains occurs between pairs og RING fingers

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*....
gi 15238647    459 KSLANNKMWRQC--GKCQHMIELSQ--GCNHITC-RCGHEFCYNCGGGW 502
Cdd:smart00647  10 SYVESNPDLKWCpaPDCSAAIIVTEeeGCNRVTCpKCGFSFCFRCKVPW 58

Rcat domain of ATP-dependent RNA helicase DEAH12 and similar proteins; This group includes Arabidopsis thaliana ATP-dependent RNA helicases DEAH11 and DEAH12, which may be bifunctional proteins that function as DEAD-box RNA helicases (EC 3.6.4.13) and RBR-type E3 ubiquitin-protein ligases (EC 2.3.2.31). As RNA helicases, they may utilize the energy from ATP hydrolysis to unwind RNA (or DNA). DEAD-box RNA helicases participate in every aspect of RNA metabolism. As E3 ubiquitin-protein ligase, they may function as part of E3 complexes, which accept ubiquitin from specific E2 ubiquitin-conjugating enzymes and then transfer it to substrates. Other members of this group may not have an RNA helicase domain. All members contain an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|..
gi 15238647 468 RQCGKCQHMIELSQGCNHITC-RCGHEFCYNC 498
Cdd:cd22585   3 KRCPKCKSLIEKIDGCNHVTCtRCGTHICWVC 34

RING finger, HC subclass, found in human homolog of Drosophila ariadne (HHARI) and similar proteins; This subfamily includes Drosophila melanogaster protein ariadne-1 (ARI-1), and its eukaryotic homologs, such as HHARI. ARI-1 is a widely expressed Drosophila RING-finger protein that localizes mainly in the cytoplasm and is required for neural development. It interacts with a novel ubiquitin-conjugating enzyme, UbcD10. HHARI, also known as H7-AP2, monocyte protein 6 (MOP-6), protein ariadne-1 homolog, Ariadne RBR E3 ubiquitin protein ligase 1 (ARIH1), ariadne-1 (ARI-1), UbcH7-binding protein, UbcM4-interacting protein, or ubiquitin-conjugating enzyme E2-binding protein 1, is an RBR-type E3 ubiquitin-protein ligase highly expressed in nuclei, where it is co-localized with nuclear bodies including Cajal, PML, and Lewy bodies. It interacts with the E2 conjugating enzymes UbcH7, UbcH8, UbcM4, and UbcD10 in human, mouse, and fly, and modulates the ubiquitylation of substrate proteins including single-minded 2 (SIM2) and translation initiation factor 4E homologous protein (4EHP). It functions as a potent mediator of DNA damage-induced translation arrest, which protects stem and cancer cells against genotoxic stress by initiating a 4EHP-mediated mRNA translation arrest. HHARI contains an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR (RING1-BRcat-Rcat) domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase function to facilitate the ubiquitination reaction. This model corresponds to the RING domain, a C3HC4-type RING-HC finger required for RBR-mediated ubiquitination.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 15238647 299 EECAICFNDIVAEGMFSVDkCRHRFCFQCVKQHVEVKLL-HGMAP--KCPHDGCKsELVID 356
Cdd:cd16626   1 MPCDICYLNYPNSYMTGLE-CGHKFCMQCWKEYLTTKIMeEGMGQtiSCPAHGCD-ILVDD 59

RING finger, HC subclass, found in topoisomerase I-binding arginine/serine-rich protein (Topors) and similar proteins; Topors, also known as topoisomerase I-binding RING finger protein, tumor suppressor p53- binding protein 3, or p53-binding protein 3 (p53BP3), is a ubiquitously expressed nuclear E3 ubiquitin-protein ligase that can ligate both ubiquitin and small ubiquitin-like modifier (SUMO) to substrate proteins in the nucleus. It contains an N-terminal C3HC4-type RING-HC finger which ligates ubiquitin to its target proteins including DNA topoisomerase I, p53, NKX3.1, H2AX, and the AAV-2 Rep78/68 proteins. As a RING-dependent E3 ubiquitin ligase, Topors works with the E2 enzymes UbcH5a, UbcH5c, and UbcH6, but not with UbcH7, CDC34, or UbcH2b. Topors acts as a tumor suppressor in various malignancies. It regulates p53 modification, suggesting it may be responsible for astrocyte elevated gene-1 (AEG-1, also known as metadherin, or LYRIC) ubiquitin modification. Plk1-mediated phosphorylation of Topors inhibits Topors-mediated sumoylation of p53, whereas p53 ubiquitination is enhanced, leading to p53 degradation. It also functions as a negative regulator of the prostate tumor suppressor NKX3.1. Moreover, Topors is associated with promyelocytic leukemia nuclear bodies, and may be involved in the cellular response to camptothecin. It also plays a key role in the turnover of H2AX protein, discriminating the type of DNA damaging stress. Furthermore, Topors is a cilia-centrosomal protein associated with autosomal dominant retinal degeneration. Mutations in TOPORS cause autosomal dominant retinitis pigmentosa (adRP).

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*..
gi 15238647 299 EECAICFNDIVAEGMFsVDKCRHRFCFQCVKQHVEVKllhgmaPKCP 345
Cdd:cd16574   2 SSCPICLDRFENEKAF-LDGCFHAFCFTCILEWSKVK------NECP 41

BRcat domain found in human homolog of Drosophila Ariadne (HHARI) and similar proteins; This subfamily includes Drosophila melanogaster protein ariadne-1 (ARI-1), and its eukaryotic homologs, such as HHARI. ARI-1 is a widely expressed Drosophila RING-finger protein that localizes mainly in the cytoplasm, and is required for neural development. It interacts with the ubiquitin-conjugating enzyme, UbcD10. HHARI is also called H7-AP2, monocyte protein 6 (MOP-6), protein ariadne-1 homolog, Ariadne RBR E3 ubiquitin protein ligase 1 (ARIH1), ariadne-1 (ARI-1), UbcH7-binding protein, UbcM4-interacting protein, or ubiquitin-conjugating enzyme E2-binding protein 1. It is an RBR-type E3 ubiquitin-protein ligase highly expressed in nuclei, where it is co-localized with nuclear bodies including Cajal, PML, and Lewy bodies. It interacts with the E2 conjugating enzymes UbcH7, UbcH8, UbcM4, and UbcD10 in human, mouse and fly, and modulates the ubiquitylation of substrate proteins including single-minded 2 (SIM2) and translation initiation factor 4E homologous protein (4EHP). It functions as a potent mediator of DNA damage-induced translation arrest, which protects stem and cancer cells against genotoxic stress by initiating a 4EHP-mediated mRNA translation arrest. HHARI contains an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the BRcat domain of HHARI and similar proteins that adopt the same fold as the Rcat domain while lacking the catalytic cysteine residue and ubiquitination activity.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|...
gi 15238647 463 NNKMWRQC-GK-CQHMIELSQG-CNHITCRCGHEFCYNCGGGW 502
Cdd:cd20343  19 CNRLLKWCpAPdCGHAVKVQYPdARPVTCKCGHTFCFACGENW 61

BRcat domain found in RING finger protein 217 (RNF217); RNF217, also termed IBR domain-containing protein 1 (IBRDC1), is a transmembrane (TM) domain-containing RBR-type E3 ubiquitin-protein ligase mainly expressed in testis and skeletal muscle with different splice variants. It interacts with the anti-apoptotic protein HAX1, and is adjacent to a translocation breakpoint involving ETV6 in childhood acute lymphoblastic leukemia (ALL). RNF217 contains a RBR domain followed by TMs. The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR (RING1-BRcat-Rcat) domain use an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase function to facilitate the ubiquitination reaction. The family corresponds to the BRcat (benign-catalytic) domain that adopts the same fold as the Rcat domain while lacking the catalytic cysteine residue and ubiquitination activity.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*..
gi 15238647 390 PRCSALmskTKISESAKSLLSLYPKSGVRRCVECRGLFCVDCKVPWHGNLSCTEYKK 446
Cdd:cd20342  10 PRCSHV---TTRPKKELIKKKKSEGGLKVQCPTCQLVWCFKCHAPWHEGITCKEYKK 63

Rcat domain found in RING finger protein 14 (RNF14); RNF14, also called androgen receptor (AR)-associated protein 54 (ARA54), HFB30, or Triad2 protein, is an RBR-type E3 ubiquitin-protein ligase that is highly expressed in the testis and interacts with class III E2s (UBE2E2, UbcH6, and UBE2E3). Its differential localization may play an important role in testicular development and spermatogenesis in humans. RNF14 functions as a transcriptional regulator of mitochondrial and immune function in muscles. It is a ligand-dependent AR co-activator that enhances AR-dependent transcriptional activation. It also may participate in enhancing cell cycle progression and cell proliferation via induction of cyclin D1. Moreover, RNF14 is crucial for colon cancer cell survival. It acts as a new enhancer of the Wnt-dependent transcriptional outputs that acts at the level of the T-cell factor/lymphoid enhancer factor (TCF/LEF)-beta-catenin complex. RNF14 contains an N-terminal RWD domain, and a C-terminal RBR domain. The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of RNF14 that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|...
gi 15238647 468 RQCGKCQHMIELSQGCNHITC-RCGHEFCYNCG 499
Cdd:cd20354  14 KPCPGCGTLIEKIDGCNKMTCtKCRTYFCWLCL 46

BRcat domain found in HOIL-1-interacting protein (HOIP) and similar proteins; HOIP, also called RING finger protein 31 (RNF31) or zinc in-between-RING-finger ubiquitin-associated domain protein, together with HOIL-1 and SHARPIN, forms the E3-ligase complex (also known as linear-ubiquitin-chain assembly complex LUBAC) that regulates NF-kappaB activity and apoptosis. It also interacts with the atypical mammalian orphan receptor DAX-1, trigger DAX-1 ubiquitination and stabilization, and participate in repressing steroidogenic gene expression. HOIP contains three Npl4 zinc fingers, a central ubiquitin-associated (UBA) domain responsible for interaction with the N-terminal ubiquitin-like domain (UBL) of HOIL-1L, an RBR domain, and a C-terminal linear chain determining domain (LDD). The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the BRcat domain of HOIP and similar proteins that adopt the same fold as the Rcat domain while lacking the catalytic cysteine residue and ubiquitination activity.

                        10        20        30
                ....*....|....*....|....*....|.
gi 15238647 419 RCVECRGLFCVDCKVPW---HGNLSCTEYKK 446
Cdd:cd20337  42 QCPQCGKVTCFKCKKPWedqHEGISCEQFQE 72

Modified RING finger, HC subclass (C4C4-type), found in HOIL-1-interacting protein (HOIP) and similar proteins; HOIP, also known as RING finger protein 31 (RNF31) or zinc in-between-RING-finger ubiquitin-associated domain protein, together with HOIL-1 and SHARPIN, forms the E3-ligase complex (also known as linear-ubiquitin-chain assembly complex LUBAC) that regulates NF-kappaB activity and apoptosis. It also interacts with the atypical mammalian orphan receptor DAX-1, trigger DAX-1 ubiquitination and stabilization, and participate in repressing steroidogenic gene expression. HOIP contains three Npl4 zinc fingers, a central ubiquitin-associated (UBA) domain responsible for the interaction with the N-terminal ubiquitin-like domain (UBL) of HOIL-1L, an RBR domain, and a C-terminal linear chain determining domain (LDD). The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR (RING1-BRcat-Rcat) domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase function to facilitate the ubiquitination reaction. This model corresponds to the RING domain, a C4C4-type RING finger motif whose overall folding is similar to that of the C3HC4-type RING-HC finger. It is required for RBR-mediated ubiquitination.

                        10        20        30
                ....*....|....*....|....*....|....*..
gi 15238647 300 ECAICFNDIVAEGMFSVDKCRHRFCFQCVKQHVEVKL 336
Cdd:cd16631   2 ECPICFNSFPRNKMVSLTSCECKICPDCFKQYFTVVI 38

RING finger, HC subclass, found in RING finger protein 10 (RNF10) and similar proteins; RNF10 is an E3 ubiquitin-protein ligase that interacts with mesenchyme Homeobox 2 (MEOX2) transcription factor, a regulator of the proliferation, differentiation and migration of vascular smooth muscle cells and cardiomyocytes; it enhances Meox2 activation of the p21 promoter. It also regulates the expression of myelin-associated glycoprotein (MAG) genes and is required for myelin production in Schwann cells of the peripheral nervous system. Moreover, RNF10 regulates retinoic acid-induced neuronal differentiation and the cell cycle exit of P19 embryonic carcinoma cells. RNF10 contains a C3HC4-type RING-HC finger and three putative nuclear localization signals.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*.
gi 15238647 300 ECAICFNDIVAEGMfsvDKCRHRFCFQCVKQHVEVKLLHGmaPKCP 345
Cdd:cd16536   2 QCPICLEPPVAPRI---TRCGHIFCWPCILRYLSLSEKKW--RKCP 42

RING finger, HC subclass, found in E3 ubiquitin-protein ligase Deltex3 (DTX3) and similar proteins; DTX3, also known as RING finger protein 154 (RNF154), is an E3 ubiquitin-protein ligase that belongs to the Deltex (DTX) family. In contrast to other DTXs, DTX3 does not contain two N-terminal Notch-binding WWE domains, but a short unique N-terminal domain, suggesting it does not interact with the intracellular domain of Notch. Its C-terminal region includes a C3HC4-type RING-HC finger, and a previously unidentified C-terminal domain.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|.
gi 15238647 299 EECAICFNDIVAegMFSVDKCRHRFCFQCVKQHVEVKllhgmaPKCPHDGC 349
Cdd:cd16711   2 ETCPICLGEIQN--KKTLDKCKHSFCEDCITRALQVK------KACPMCGE 44

Zinc finger, C3HC4 type (RING finger); The C3HC4 type zinc-finger (RING finger) is a cysteine-rich domain of 40 to 60 residues that coordinates two zinc ions, and has the consensus sequence: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-C-X2-C-X(4-48)-C-X2-C where X is any amino acid. Many proteins containing a RING finger play a key role in the ubiquitination pathway.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*
gi 15238647   301 CAICFnDIVAEGMFSvDKCRHRFCFQCVKQHVEvkllhGMAPKCP 345
Cdd:pfam00097   1 CPICL-EEPKDPVTL-LPCGHLFCSKCIRSWLE-----SGNVTCP 38

Rcat domain found in HOIL-1-interacting protein (HOIP) and similar proteins; HOIP, also called RING finger protein 31 (RNF31) or zinc in-between-RING-finger ubiquitin-associated domain protein, together with HOIL-1 and SHARPIN, forms the E3-ligase complex (also known as linear-ubiquitin-chain assembly complex LUBAC) that regulates NF-kappaB activity and apoptosis. It also interacts with the atypical mammalian orphan receptor DAX-1, trigger DAX-1 ubiquitination and stabilization, and participate in repressing steroidogenic gene expression. HOIP contains three Npl4 zinc fingers, a central ubiquitin-associated (UBA) domain responsible for the interaction with the N-terminal ubiquitin-like domain (UBL) of HOIL-1L, an RBR domain, and a C-terminal linear chain determining domain (LDD). The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of HOIP that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.

                        10        20        30
                ....*....|....*....|....*....|...
gi 15238647 469 QCGKCQHMIELSQG-CNHITC-RCGHEFCYNCG 499
Cdd:cd20351  18 DCPKCKFRYALAKGgCMHFTCtQCRHEFCSGCY 50

Modified RING finger, HC subclass (C3HC3D-type), found in heme-oxidized IRP2 ubiquitin ligase 1 (HOIL-1) and similar proteins; HOIL-1, also known as RBCK1, HOIL-1L, RanBP-type and C3HC4-type zinc finger-containing protein 1, HBV-associated factor 4, Hepatitis B virus X-associated protein 4, RING finger protein 54 (RNF54), ubiquitin-conjugating enzyme 7-interacting protein 3, or UbcM4-interacting protein 28 (UIP28), together with E3 ubiquitin-protein ligase RNF31 (also known as HOIP) and SHANK-associated RH domain interacting protein (SHARPIN), form the E3-ligase complex (also known as linear-ubiquitin-chain assembly complex LUBAC) that regulates NF-kappaB activity and apoptosis through conjugation of linear polyubiquitin chains to NF-kappaB essential modulator (also known as NEMO or IKBKG). HOIL-1 plays a crucial role in TNF-alpha-mediated NF-kappaB activation. It also functions as an ubiquitin-protein ligase E3 that interacts with not only PKCbeta, but also PKCzeta. It can recognize heme-oxidized IRP2 (iron regulatory protein2) and is thought to affect the turnover of oxidatively damaged proteins. HOIL-1 contains an N-terminal ubiqutin-like (UBL) domain and an Npl4 zinc-finger (NZF) domain, which regulate the interaction with the LUBAC subunit RNF31 and ubiquitin, respectively. The NZF domain belongs to the RanBP2-type zinc finger (zf-RanBP2) domain superfamily. In addition, HOIL-1 has an RBR domain that was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been corrected as RING-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR (RING1-BRcat-Rcat) domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase function to facilitate the ubiquitination reaction. This model corresponds to the RING domain, a modified C3HC3D-type RING-HC finger required for RBR-mediated ubiquitination.

                        10        20        30
                ....*....|....*....|....*....|....
gi 15238647 300 ECAICFNDIVAEGMFSVDKCRHRFCFQCVKQHVE 333
Cdd:cd16633   9 ECPICFDDVPPGEGVVLRECLHSFCRECLRGAIQ 42

Eukaryotic RNase H is essential and is longer and more complex than their prokaryotic counterparts; Ribonuclease H (RNase H) is classified into two families, type 1 (prokaryotic RNase HI, eukaryotic RNase H1 and viral RNase H) and type 2 (prokaryotic RNase HII and HIII, and eukaryotic RNase H2). RNase H is an endonuclease that cleaves the RNA strand of an RNA/DNA hybrid in a sequence non-specific manner. RNase H is involved in DNA replication, repair and transcription. One of the important functions of RNase H is to remove Okazaki fragments during DNA replication. RNase H is widely present in various organisms, including bacteria, archaea and eukaryote and most prokaryotic and eukaryotic genomes contain multiple RNase H genes. Despite the lack of amino acid sequence homology, type 1 and type 2 RNase H share a main-chain fold and steric configurations of the four acidic active-site (DEDD) residues and have the same catalytic mechanism and functions in cells. Eukaryotic RNase H is longer and more complex than in prokaryotes. Almost all eukaryotic RNase HI have highly conserved regions at their N-termini called hybrid binding domain (HBD). It is speculated that the HBD contributes to binding the RNA/DNA hybrid. Prokaryotes and some single-cell eukaryotes do not require RNase H for viability, but RNase H is essential in higher eukaryotes. RNase H knockout mice lack mitochondrial DNA replication and die as embryos.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 15238647 198 AELKALIRGLTEALKLGIKHIVFFCDSypifQYVT---GKWMAKQKKISLLL---------DDLQSIMQHFSSYQhvlva 265
Cdd:cd09280  46 AELLAVIHALEQAPEEGIRKLEIRTDS----KYAInciTKWIPKWKKNGWKTskgkpvknqDLIKELDKLLRKRG----- 116

                        90       100
                ....*....|....*....|....*..
gi 15238647 266 rNDVKF--------------AYKLARE 278
Cdd:cd09280 117 -IKVKFehvkghsgdpgneeADRLARE 142