Mpr1p, Pad1p N-terminal (MPN) domains; MPN (also known as Mov34, PAD-1, JAMM, JAB, MPN+) domains are found in the N-terminal termini of proteins with a variety of functions; they are components of the proteasome regulatory subunits, the signalosome (CSN), eukaryotic translation initiation factor 3 (eIF3) complexes, and regulators of transcription factors. These domains are isopeptidases that release ubiquitin from ubiquitinated proteins (thus having deubiquitinating (DUB) activity) that are tagged for degradation. Catalytically active MPN domains contain a metalloprotease signature known as the JAB1/MPN/Mov34 metalloenzyme (JAMM) motif. For example, Rpn11 (also known as POH1 or PSMD14), a subunit of the 19S proteasome lid is involved in the ATP-dependent degradation of ubiquitinated proteins, contains the conserved JAMM motif involved in zinc ion coordination. Poh1 is a regulator of c-Jun, an important regulator of cell proliferation, differentiation, survival and death. JAB1 is a component of the COP9 signalosome (CSN), a regulatory particle of the ubiquitin (Ub)/26S proteasome system occurring in all eukaryotic cells; it cleaves the ubiquitin-like protein NEDD8 from the cullin subunit of the SCF (Skp1, Cullins, F-box proteins) family of E3 ubiquitin ligases. AMSH (associated molecule with the SH3 domain of STAM, also known as STAMBP), a member of JAMM/MPN+ deubiquitinases (DUBs), specifically cleaves Lys 63-linked polyubiquitin (poly-Ub) chains, thus facilitating the recycling and subsequent trafficking of receptors to the cell surface. Similarly, BRCC36, part of the nuclear complex that includes BRCA1 protein and is targeted to DNA damage foci after irradiation, specifically disassembles K63-linked polyUb. BRCC36 is aberrantly expressed in sporadic breast tumors, indicative of a potential role in the pathogenesis of the disease. Some variants of the JAB1/MPN domains lack key residues in their JAMM motif and are unable to coordinate a metal ion. Comparisons of key catalytic and metal binding residues explain why the MPN-containing proteins Mov34/PSMD7, Rpn8, CSN6, Prp8p, and the translation initiation factor 3 subunits f (p47) and h (p40) do not show catalytic isopeptidase activity. It has been proposed that the MPN domain in these proteins has a primarily structural function.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 79317567  45 MCQAMNEVEVFSIQNERELYPVGWIHTHPSQGCFMSSVDLHTHYSYQVMVPEAFAIVVAPtdSSKSYGIFKLTDPGGMEV 124
Cdd:cd08066  57 SCQTTNEEELFDFQDQHDLITLGWIHTHPTQTCFLSSVDLHTHCSYQLMLPEAIAIVCAP--KYNEFGIFRLTDPPGLDE 134

                        90       100       110       120
                ....*....|....*....|....*....|....*....|..
gi 79317567 125 LRGCSETGFHPHKEPedgNPVYEHCSNVYKNSNLRFEIFDLR 166
Cdd:cd08066 135 ILNCKKTGFHPHPKD---PPLYEDCGHVIWKDQLKVTVVDLR 173

Mov34/MPN/PAD-1 family; AMSH (associated molecule with the Src homology 3 domain (SH3) of STAM (signal-transducing adapter molecule, also known as STAMBP)) and AMSH-like proteins (AMSH-LP) are members of JAMM/MPN+ deubiquitinases (DUBs), with Zn2+-dependent ubiquitin isopeptidase activity. AMSH specifically cleaves Lys 63 and not Lys48-linked polyubiquitin (poly-Ub) chains, thus facilitating the recycling and subsequent trafficking of receptors to the cell surface. AMSH and AMSH-LP are anchored on the early endosomal membrane via interaction with the clathrin coat. AMSH shares a common SH3-binding site with another endosomal DUB, UBPY (ubiquitin-specific protease Y; also known as USP8), the latter being a cysteine protease that does not discriminate between Lys48 and Lys63-linked ubiquitin. AMSH is involved in the degradation of EGF receptor (EGFR) and possibly other ubiquitinated endocytosed proteins. AMSH also interacts with CHMP1, CHMP2, and CHMP3 proteins, all of which are components of ESCRT-III, suggested to be required for EGFR down-regulation. The function of AMSH-LP has not been elucidated; however, it exhibits two fundamentally distinct features from AMSH: first, there is a substitution in the critical amino acid residue in the SH3-binding motif (SBM) in the human AMSH-LP, but not in its mouse ortholog, and lacks STAM-binding ability; second, AMSH-LP lacks the ability to interact with CHMP proteins. It is therefore likely that AMSH and AMSH-LP play different roles on early endosomes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 79317567  45 MCQAMNEVEVFSIQNERELYPVGWIHTHPSQGCFMSSVDLHTHYSYQVMVPEAFAIVVAPtdSSKSYGIFKLTDPGGMEV 124
Cdd:cd08066  57 SCQTTNEEELFDFQDQHDLITLGWIHTHPTQTCFLSSVDLHTHCSYQLMLPEAIAIVCAP--KYNEFGIFRLTDPPGLDE 134

                        90       100       110       120
                ....*....|....*....|....*....|....*....|..
gi 79317567 125 LRGCSETGFHPHKEPedgNPVYEHCSNVYKNSNLRFEIFDLR 166
Cdd:cd08066 135 ILNCKKTGFHPHPKD---PPLYEDCGHVIWKDQLKVTVVDLR 173

JAB1/Mov34/MPN/PAD-1 ubiquitin protease; Members of this family are found in proteasome regulatory subunits, eukaryotic initiation factor 3 (eIF3) subunits and regulators of transcription factors. This family is also known as the MPN domain and PAD-1-like domain, JABP1 domain or JAMM domain. These are metalloenzymes that function as the ubiquitin isopeptidase/ deubiquitinase in the ubiquitin-based signalling and protein turnover pathways in eukaryotes. Versions of the domain in prokaryotic cognates of the ubiquitin-modification pathway are shown to have a similar role, and the archael protein from Haloferax volcanii is found to cleave ubiquitin-like small archaeal modifier proteins (SAMP1/2) from protein conjugates.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 79317567    49 MNEVEVFSIQNERELyPVGWIHTHPsQGCFMSSVDLHTHYSYQVMVPE 96
Cdd:pfam01398  72 ENMHEMLKKVNRKEE-VVGWYHTHP-GLCWLSSVDVHTHALYQRMIPE 117

Mov34/MPN/PAD-1 family; AMSH (associated molecule with the Src homology 3 domain (SH3) of STAM (signal-transducing adapter molecule, also known as STAMBP)) and AMSH-like proteins (AMSH-LP) are members of JAMM/MPN+ deubiquitinases (DUBs), with Zn2+-dependent ubiquitin isopeptidase activity. AMSH specifically cleaves Lys 63 and not Lys48-linked polyubiquitin (poly-Ub) chains, thus facilitating the recycling and subsequent trafficking of receptors to the cell surface. AMSH and AMSH-LP are anchored on the early endosomal membrane via interaction with the clathrin coat. AMSH shares a common SH3-binding site with another endosomal DUB, UBPY (ubiquitin-specific protease Y; also known as USP8), the latter being a cysteine protease that does not discriminate between Lys48 and Lys63-linked ubiquitin. AMSH is involved in the degradation of EGF receptor (EGFR) and possibly other ubiquitinated endocytosed proteins. AMSH also interacts with CHMP1, CHMP2, and CHMP3 proteins, all of which are components of ESCRT-III, suggested to be required for EGFR down-regulation. The function of AMSH-LP has not been elucidated; however, it exhibits two fundamentally distinct features from AMSH: first, there is a substitution in the critical amino acid residue in the SH3-binding motif (SBM) in the human AMSH-LP, but not in its mouse ortholog, and lacks STAM-binding ability; second, AMSH-LP lacks the ability to interact with CHMP proteins. It is therefore likely that AMSH and AMSH-LP play different roles on early endosomes.

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 79317567  45 MCQAMNEVEVFSIQNERELYPVGWIHTHPSQGCFMSSVDLHTHYSYQVMVPEAFAIVVAPtdSSKSYGIFKLTDPGGMEV 124
Cdd:cd08066  57 SCQTTNEEELFDFQDQHDLITLGWIHTHPTQTCFLSSVDLHTHCSYQLMLPEAIAIVCAP--KYNEFGIFRLTDPPGLDE 134

                        90       100       110       120
                ....*....|....*....|....*....|....*....|..
gi 79317567 125 LRGCSETGFHPHKEPedgNPVYEHCSNVYKNSNLRFEIFDLR 166
Cdd:cd08066 135 ILNCKKTGFHPHPKD---PPLYEDCGHVIWKDQLKVTVVDLR 173

Mpr1p, Pad1p N-terminal (MPN) domains; MPN (also known as Mov34, PAD-1, JAMM, JAB, MPN+) domains are found in the N-terminal termini of proteins with a variety of functions; they are components of the proteasome regulatory subunits, the signalosome (CSN), eukaryotic translation initiation factor 3 (eIF3) complexes, and regulators of transcription factors. These domains are isopeptidases that release ubiquitin from ubiquitinated proteins (thus having deubiquitinating (DUB) activity) that are tagged for degradation. Catalytically active MPN domains contain a metalloprotease signature known as the JAB1/MPN/Mov34 metalloenzyme (JAMM) motif. For example, Rpn11 (also known as POH1 or PSMD14), a subunit of the 19S proteasome lid is involved in the ATP-dependent degradation of ubiquitinated proteins, contains the conserved JAMM motif involved in zinc ion coordination. Poh1 is a regulator of c-Jun, an important regulator of cell proliferation, differentiation, survival and death. JAB1 is a component of the COP9 signalosome (CSN), a regulatory particle of the ubiquitin (Ub)/26S proteasome system occurring in all eukaryotic cells; it cleaves the ubiquitin-like protein NEDD8 from the cullin subunit of the SCF (Skp1, Cullins, F-box proteins) family of E3 ubiquitin ligases. AMSH (associated molecule with the SH3 domain of STAM, also known as STAMBP), a member of JAMM/MPN+ deubiquitinases (DUBs), specifically cleaves Lys 63-linked polyubiquitin (poly-Ub) chains, thus facilitating the recycling and subsequent trafficking of receptors to the cell surface. Similarly, BRCC36, part of the nuclear complex that includes BRCA1 protein and is targeted to DNA damage foci after irradiation, specifically disassembles K63-linked polyUb. BRCC36 is aberrantly expressed in sporadic breast tumors, indicative of a potential role in the pathogenesis of the disease. Some variants of the JAB1/MPN domains lack key residues in their JAMM motif and are unable to coordinate a metal ion. Comparisons of key catalytic and metal binding residues explain why the MPN-containing proteins Mov34/PSMD7, Rpn8, CSN6, Prp8p, and the translation initiation factor 3 subunits f (p47) and h (p40) do not show catalytic isopeptidase activity. It has been proposed that the MPN domain in these proteins has a primarily structural function.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 79317567  53 EVFSIQNERELYPVGWIHTHPSQGCFMSSVDLHTHYSYQVMVPEAFAIVVAPT--DSSKSYGIF 114
Cdd:cd07767  53 YLDFKKLNAGLRIVGWYHTHPKPSCFLSPNDLATHELFQRYFPEKVMIIVDVKpkDLGNSWKCY 116

JAB1/Mov34/MPN/PAD-1 ubiquitin protease; Members of this family are found in proteasome regulatory subunits, eukaryotic initiation factor 3 (eIF3) subunits and regulators of transcription factors. This family is also known as the MPN domain and PAD-1-like domain, JABP1 domain or JAMM domain. These are metalloenzymes that function as the ubiquitin isopeptidase/ deubiquitinase in the ubiquitin-based signalling and protein turnover pathways in eukaryotes. Versions of the domain in prokaryotic cognates of the ubiquitin-modification pathway are shown to have a similar role, and the archael protein from Haloferax volcanii is found to cleave ubiquitin-like small archaeal modifier proteins (SAMP1/2) from protein conjugates.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|....*...
gi 79317567    49 MNEVEVFSIQNERELyPVGWIHTHPsQGCFMSSVDLHTHYSYQVMVPE 96
Cdd:pfam01398  72 ENMHEMLKKVNRKEE-VVGWYHTHP-GLCWLSSVDVHTHALYQRMIPE 117

Mov34/MPN/PAD-1 family: BRCC36, a subunit of BRCA1-A complex; BRCC36 (BRCA1-A complex subunit BRCC36; BRCA1/BRCA2-containing complex subunit 36; BRCA1/BRCA2-containing complex subunit 3; BRCC3; BRISC complex subunit BRCC36; BRCC36 isopeptidase complex; Lys-63-specific deubiquitinase BRCC36) and BRCC36-like domains are members of JAMM/MPN+ deubiquitinases (DUBs), possibly with Zn2+-dependent ubiquitin isopeptidase activity. BRCC36 is part of the BRCA1/BRCA2/BARD1-containing nuclear complex that displays an E3 ubiquitin ligase activity. It is targeted to DNA damage foci after irradiation; RAP80 recruits the Abraxas-BRCC36-BRCA1-BARD1 complex to DNA double strand breaks (DSBs) for DNA repair through specific recognition of Lys 63-linked polyubiquitinated proteins by its tandem ubiquitin-interacting motifs. A new protein, MERIT40 (mediator of RAP80 interactions and targeting 40 kDa), also named NBA1 (new component of the BRCA1 A complex), exists in the same BRCA1-containing complex and is essential for the integrity of the complex. There are studies suggesting that MERIT40/NBA1 ties BRCA1 complex integrity, DSB recognition, and ubiquitin chain activities to the DNA damage response. It has also been shown that BRCA1-containing complex resembles the lid complex of the 26S proteasome.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|....*....
gi 79317567  45 MCQAMNEVEVFSIQNERELYPVGWIHTHPSQGCFMSSVDLHTHYSYQVM 93
Cdd:cd08068  71 LSAASTEAERLTEETGRPMRVVGWYHSHPHITVWPSHVDVRTQAMYQMM 119

Mpr1p, Pad1p N-terminal (MPN) domains without isopeptidase activity found in splicing factor Prp8; Members of this family are found in pre-mRNA-processing factor 8 (Prp8) which is a critical splicing factor, interacting with several other spliceosomal proteins, snRNAs, and the pre-mRNA, thus organizing and stabilizing the spliceosome catalytic core. Prp8 is one of the largest and most highly conserved of nuclear proteins, occupying a central position in the catalytic core of the spliceosome. Its C-terminal domain exhibits a JAB1/MPN-like core similar to deubiquitinating enzymes, but does not show catalytic isopeptidase activity, possibly because the putative isopeptidase center is covered by insertions and terminal appendices that are grafted onto this core, thus impairing the metal binding site. It is proposed that this domain is a protein interaction domain instead of a Zn(2+)-dependent metalloenzyme as proposed for some MPN proteins. The DEAD-box protein Brr2 and the GTPase Snu114 bind to the Prp8 C-terminus, a region where mutations in human Prp8 (hPrp8) cause a severe form of the genetic disorder retinitis pigmentosa, RP13, which leads to progressive photoreceptor degeneration in the retina and eventual blindness. At the N-terminus of Prp8, there are several domains, including a highly variable nuclear localization signal (NLS) motif rich in prolines, a conserved RNA recognition motif (RRM), and U5 and U6 snRNA binding sites.

                        10        20
                ....*....|....*....|....*..
gi 79317567  61 RELYPVGWIHTHPSQGCFMSSVDLHTH 87
Cdd:cd08056 104 EDLEPLGWIHTQPNELPQLSPQDVTTH 130