Src Homology 3 domain superfamily; Src Homology 3 (SH3) domains are protein interaction domains that bind proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. Thus, they are referred to as proline-recognition domains (PRDs). SH3 domains are less selective and show more diverse specificity compared to other PRDs. They have been shown to bind peptide sequences that lack the PxxP motif; examples include the PxxDY motif of Eps8 and the RKxxYxxY sequence in SKAP55. SH3 domain containing proteins play versatile and diverse roles in the cell, including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies, among others. Many members of this superfamily are adaptor proteins that associate with a number of protein partners, facilitating complex formation and signal transduction.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 40804468  99 KPVAFAVRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLD 166
Cdd:cd12041   1 KPVAFAVRTNVGYNPSPGDDVPVQGMAISFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLE 68

Src Homology 3 domain of Voltage-dependent L-type calcium channel subunit beta-1; The beta1 subunit of voltage-dependent calcium channels (Ca(V)s) is one of four beta subunits present in vertebrates. It is the only beta subunit, as the beta1a variant, expressed in skeletal muscle; the beta1b variant is also widely expressed in other tissues including the heart and brain. Knockout of the beta1 gene in mice results in embryonic lethality, demonstrating its importance in development. Ca(V)s are multi-protein complexes that regulate the entry of calcium into cells. They impact muscle contraction, neuronal migration, hormone and neurotransmitter release, and the activation of calcium-dependent signaling pathways. They are composed of four subunits: alpha1, alpha2delta, beta, and gamma. The beta subunit is a soluble and intracellular protein that interacts with the transmembrane alpha1 subunit. It facilitates the trafficking and proper localization of the alpha1 subunit to the cellular plasma membrane. Vertebrates contain four different beta subunits from distinct genes (beta1-4); each exists as multiple splice variants. All are expressed in the brain while other tissues show more specific expression patterns. The beta subunits show similarity to MAGUK (membrane-associated guanylate kinase) proteins in that they contain SH3 and inactive guanylate kinase (GuK) domains; however, they do not appear to contain a PDZ domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 40804468  99 KPVAFAVRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLD 166
Cdd:cd12041   1 KPVAFAVRTNVGYNPSPGDDVPVQGMAISFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLE 68

Voltage gated calcium channel subunit beta domain 4Aa N terminal; The beta subunit of voltage gated calcium channels is coded for by four genes 1-4. Gene 4 can produce two types of beta4A domain (beta4Aa and beta4Ab) according to how the gene splicing is carried out. This family is part of the beta4Aa N terminal domain. It is made up of an alpha helix and a beta strand. It is thought to regulate the channel properties through protein-protein interactions with non Ca channel proteins.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 40804468    58 GSAESYTSRPSDSDVSLEEDREALRKEAERQALAQLEKAKTK 99
Cdd:pfam12052   1 GSADSNTSRPSDSDLSLEEDREALRREAERQALAQLEKAKSK 42

SH3 domain; SH3 (Src homology 3) domains are often indicative of a protein involved in signal transduction related to cytoskeletal organization. First described in the Src cytoplasmic tyrosine kinase. The structure is a partly opened beta barrel.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|.
gi 40804468   111 YNPSPGDEvpvqgvaITFEPKDFLHIKEKYNNDWWIGRLVKEgcEVGFIPS 161
Cdd:pfam00018   6 YTAQEPDE-------LSFKKGDIIIVLEKSEDGWWKGRNKGG--KEGLIPS 47

Src Homology 3 domain of Voltage-dependent L-type calcium channel subunit beta-1; The beta1 subunit of voltage-dependent calcium channels (Ca(V)s) is one of four beta subunits present in vertebrates. It is the only beta subunit, as the beta1a variant, expressed in skeletal muscle; the beta1b variant is also widely expressed in other tissues including the heart and brain. Knockout of the beta1 gene in mice results in embryonic lethality, demonstrating its importance in development. Ca(V)s are multi-protein complexes that regulate the entry of calcium into cells. They impact muscle contraction, neuronal migration, hormone and neurotransmitter release, and the activation of calcium-dependent signaling pathways. They are composed of four subunits: alpha1, alpha2delta, beta, and gamma. The beta subunit is a soluble and intracellular protein that interacts with the transmembrane alpha1 subunit. It facilitates the trafficking and proper localization of the alpha1 subunit to the cellular plasma membrane. Vertebrates contain four different beta subunits from distinct genes (beta1-4); each exists as multiple splice variants. All are expressed in the brain while other tissues show more specific expression patterns. The beta subunits show similarity to MAGUK (membrane-associated guanylate kinase) proteins in that they contain SH3 and inactive guanylate kinase (GuK) domains; however, they do not appear to contain a PDZ domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 40804468  99 KPVAFAVRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLD 166
Cdd:cd12041   1 KPVAFAVRTNVGYNPSPGDDVPVQGMAISFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLE 68

Src Homology 3 domain of Voltage-dependent L-type calcium channel subunit beta2; The beta2 subunit of voltage-dependent calcium channels (Ca(V)s) is one of four beta subunits present in vertebrates. It is expressed in the heart and is present in specific neuronal cells including cerebellar Purkinje cells, hippocampal pyramidal neurons, and photoreceptors. Knockout of the beta2 gene in mice results in embryonic lethality, demonstrating its importance in development. Ca(V)s are multi-protein complexes that regulate the entry of calcium into cells. They impact muscle contraction, neuronal migration, hormone and neurotransmitter release, and the activation of calcium-dependent signaling pathways. They are composed of four subunits: alpha1, alpha2delta, beta, and gamma. The beta subunit is a soluble and intracellular protein that interacts with the transmembrane alpha1 subunit. It facilitates the trafficking and proper localization of the alpha1 subunit to the cellular plasma membrane. Vertebrates contain four different beta subunits from distinct genes (beta1-4); each exists as multiple splice variants. All are expressed in the brain while other tissues show more specific expression patterns. The beta subunits show similarity to MAGUK (membrane-associated guanylate kinase) proteins in that they contain SH3 and inactive guanylate kinase (GuK) domains; however, they do not appear to contain a PDZ domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 40804468  98 TKPVAFAVRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLD 166
Cdd:cd12040   1 TKPVAFAVRTNVGYSAAHEDDVPVPGMAISFEAKDFLHVKEKFNNDWWIGRLVKEGCEIGFIPSPVKLE 69

Guanylate kinase homologues; Active enzymes catalyze ATP-dependent phosphorylation of GMP to GDP. Structure resembles that of adenylate kinase. So-called membrane-associated guanylate kinase homologues (MAGUKs) do not possess guanylate kinase activities; instead at least some possess protein-binding functions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 40804468    238 SLKGYEVTDMMQK---ALFDFLKHRFDGRISITRVTADISLAKRSVLNNPSKH-IIIERSNTRSSLaeVQSEIERIFELA 313
Cdd:smart00072   3 VGKGTLLAELIQEipdAFERVVSHTTRPPRPGEVNGVDYHFVSKEEFEDDIKSgLFLEWGEYEGNY--YGTSKETIRQVA 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 40804468    314 RTLQLVALDADtINHPAQLSKTSLAPIIVYIKITSPKVLQRLIKSRGKSQSKHLNVQIAASEKLAQCpPEMFDIILDENQ 393
Cdd:smart00072  81 EKGKHCLLDID-PQGVKQLRKAQLYPIVIFIAPPSSEELERRLRQRGTETSERIQKRLAAAQKEAQE-YHLFDYVIVNDD 158

                          170
                   ....*....|....*.
gi 40804468    394 LEDACEHLAEYLEAYW 409
Cdd:smart00072 159 LEDAYEELKEILEAEQ 174

Voltage gated calcium channel subunit beta domain 4Aa N terminal; The beta subunit of voltage gated calcium channels is coded for by four genes 1-4. Gene 4 can produce two types of beta4A domain (beta4Aa and beta4Ab) according to how the gene splicing is carried out. This family is part of the beta4Aa N terminal domain. It is made up of an alpha helix and a beta strand. It is thought to regulate the channel properties through protein-protein interactions with non Ca channel proteins.

                          10        20        30        40
                  ....*....|....*....|....*....|....*....|..
gi 40804468    58 GSAESYTSRPSDSDVSLEEDREALRKEAERQALAQLEKAKTK 99
Cdd:pfam12052   1 GSADSNTSRPSDSDLSLEEDREALRREAERQALAQLEKAKSK 42

Src Homology 3 domain of Membrane Protein, Palmitoylated 1 (or MAGUK p55 subfamily member 1)-like proteins; This subfamily includes MPP1, CASK (Calcium/calmodulin-dependent Serine protein Kinase), Caenorhabditis elegans lin-2, and similar proteins. MPP1 and CASK are scaffolding proteins from the MAGUK (membrane-associated guanylate kinase) protein family, which is characterized by the presence of a core of three domains: PDZ, SH3, and guanylate kinase (GuK). In addition, they also have the Hook (Protein 4.1 Binding) motif in between the SH3 and GuK domains. The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. CASK and lin-2 also contain an N-terminal calmodulin-dependent kinase (CaMK)-like domain and two L27 domains. MPP1 is ubiquitously-expressed and plays roles in regulating neutrophil polarity, cell shape, hair cell development, and neural development and patterning of the retina. CASK is highly expressed in the mammalian nervous system and plays roles in synaptic protein targeting, neural development, and gene expression regulation. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*....
gi 40804468 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCEV-GFIPSP 162
Cdd:cd12035   2 VRAQFDYDPSKDDLIPCQQAGIAFKTGDILQIISKDDHNWWQARKPGASKEPaGLIPSP 60

Src Homology 3 domain of Calcium/calmodulin-dependent Serine protein Kinase; CASK is a scaffolding protein that is highly expressed in the mammalian nervous system and plays roles in synaptic protein targeting, neural development, and gene expression regulation. CASK interacts with many different binding partners including parkin, neurexin, syndecans, calcium channel proteins, caskin, among others, to perform specific functions in different subcellular locations. Disruption of the CASK gene in mice results in neonatal lethality while mutations in the human gene have been associated with X-linked mental retardation. Drosophila CASK is associated with both pre- and postsynaptic membranes and is crucial in synaptic transmission and vesicle cycling. CASK contains an N-terminal calmodulin-dependent kinase (CaMK)-like domain, two L27 domains, followed by the core of three domains characteristic of MAGUK (membrane-associated guanylate kinase) proteins: PDZ, SH3, and guanylate kinase (GuK). In addition, it also contains the Hook (Protein 4.1 Binding) motif in between the SH3 and GuK domains. The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*....
gi 40804468 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKE-GCEVGFIPSP 162
Cdd:cd12081   2 VRAQFEYDPLKDDLIPCKQAGIRFRVGDILQIISKDDHNWWQAKLENSkNGTAGLIPSP 60

Src Homology 3 domain of Disks large homolog proteins; The DLG-like proteins are scaffolding proteins that cluster at synapses and are also called PSD (postsynaptic density)-95 proteins or SAPs (synapse-associated proteins). They play important roles in synaptic development and plasticity, cell polarity, migration and proliferation. They are members of the MAGUK (membrane-associated guanylate kinase) protein family, which is characterized by the presence of a core of three domains: PDZ, SH3, and guanylate kinase (GuK). The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. DLG-like proteins contain three PDZ domains and varying N-terminal regions. All DLG proteins exist as alternatively-spliced isoforms. Vertebrates contain four DLG proteins from different genes, called DLG1-4. DLG4 and DLG2 are found predominantly at postsynaptic sites and they mediate surface ion channel and receptor clustering. DLG3 is found axons and some presynaptic terminals. DLG1 interacts with AMPA-type glutamate receptors and is critical in their maturation and delivery to synapses. The SH3 domain of DLG4 binds and clusters the kainate subgroup of glutamate receptors via two proline-rich sequences in their C-terminal tail. It also binds AKAP79/150 (A-kinase anchoring protein). SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|
gi 40804468 105 VRTNVGYNPSPGDEVPVQGVAitFEPKDFLHIKEKYNNDWWIGRLVKEGCE---VGFIPS 161
Cdd:cd11861   2 VRALFDYDPSRDSGLPSQGLS--FKFGDILHVTNASDDEWWQARRVTPNGEeeeVGVIPS 59

SH3 domain; SH3 (Src homology 3) domains are often indicative of a protein involved in signal transduction related to cytoskeletal organization. First described in the Src cytoplasmic tyrosine kinase. The structure is a partly opened beta barrel.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|.
gi 40804468   111 YNPSPGDEvpvqgvaITFEPKDFLHIKEKYNNDWWIGRLVKEgcEVGFIPS 161
Cdd:pfam00018   6 YTAQEPDE-------LSFKKGDIIIVLEKSEDGWWKGRNKGG--KEGLIPS 47

Src Homology 3 domain of Disks Large homolog 4; DLG4, also called postsynaptic density-95 (PSD95) or synapse-associated protein 90 (SAP90), is a scaffolding protein that clusters at synapses and plays an important role in synaptic development and plasticity. It is responsible for the membrane clustering and retention of many transporters and receptors such as potassium channels and PMCA4b, a P-type ion transport ATPase, among others. DLG4 is a member of the MAGUK (membrane-associated guanylate kinase) protein family, which is characterized by the presence of a core of three domains: PDZ, SH3, and guanylate kinase (GuK). The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. DLG4 contains three PDZ domains. The SH3 domain of DLG4 binds and clusters the kainate subgroup of glutamate receptors via two proline-rich sequences in their C-terminal tail. It also binds AKAP79/150 (A-kinase anchoring protein). SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40
                ....*....|....*....|....*....|....*....|
gi 40804468 125 AITFEPKDFLHIKEKYNNDWWIGRLV---KEGCEVGFIPS 161
Cdd:cd12030  22 ALSFRFGDVLHVIDAGDEEWWQARRVhsdSETEEIGFIPS 61

Src Homology 3 domain of Membrane Protein, Palmitoylated 5 (or MAGUK p55 subfamily member 5); MPP5, also called PALS1 (Protein associated with Lin7) or Nagie oko protein in zebrafish or Stardust in Drosophila, is a scaffolding protein which associates with Crumbs homolog 1 (CRB1), CRB2, or CRB3 through its PDZ domain and with PALS1-associated tight junction protein (PATJ) or multi-PDZ domain protein 1 (MUPP1) through its L27 domain. The resulting tri-protein complexes are core proteins of the Crumb complex, which localizes at tight junctions or subapical regions, and is involved in the maintenance of apical-basal polarity in epithelial cells and the morphogenesis and function of photoreceptor cells. MPP5 is critical for the proper stratification of the retina and is also expressed in T lymphocytes where it is important for TCR-mediated activation of NFkB. Drosophila Stardust exists in several isoforms, some of which show opposing functions in photoreceptor cells, which suggests that the relative ratio of different Crumbs complexes regulates photoreceptor homeostasis. MPP5 contains two L27 domains followed by the core of three domains characteristic of MAGUK (membrane-associated guanylate kinase) proteins: PDZ, SH3, and guanylate kinase (GuK). In addition, it also contains the Hook (Protein 4.1 Binding) motif in between the SH3 and GuK domains. The GuK domain in MAGUK proteins is enzymatically inactive; instead, the domain mediates protein-protein interactions and associates intramolecularly with the SH3 domain. SH3 domains are protein interaction domains that bind to proline-rich ligands with moderate affinity and selectivity, preferentially to PxxP motifs. They play versatile and diverse roles in the cell including the regulation of enzymes, changing the subcellular localization of signaling pathway components, and mediating the formation of multiprotein complex assemblies.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 40804468 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWigRLVKEGCE-----VGFIPSPV 163
Cdd:cd12036   2 VRAHFDYDPEDDPYIPCRELGLSFQKGDILHVISQEDPNWW--QAYREGEEdnqslAGLIPSKS 63