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 530412807  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 530412807   58 GSAESYTSRPSDSDVSLEEDREALRKEAERQALAQLEKAKTK 99
Cdd:pfam12052   1 GSADSNTSRPSDSDLSLEEDREALRREAERQALAQLEKAKSK 42

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 530412807  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 530412807   58 GSAESYTSRPSDSDVSLEEDREALRKEAERQALAQLEKAKTK 99
Cdd:pfam12052   1 GSADSNTSRPSDSDLSLEEDREALRREAERQALAQLEKAKSK 42

Src homology 3 domains; Src homology 3 (SH3) domains bind to target proteins through sequences containing proline and hydrophobic amino acids. Pro-containing polypeptides may bind to SH3 domains in 2 different binding orientations.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|.
gi 530412807   101 VAFAVRTNVGYNPSPGDEvpvqgvaITFEPKDFLHIKEKYNNDWWIGRLVKEgcEVGFIPS 161
Cdd:smart00326   1 EGPQVRALYDYTAQDPDE-------LSFKKGDIITVLEKSDDGWWKGRLGRG--KEGLFPS 52

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 530412807  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 530412807  98 TKPVAFAVRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPSPVKLD 166
Cdd:cd12040    1 TKPVAFAVRTNVGYSAAHEDDVPVPGMAISFEAKDFLHVKEKFNNDWWIGRLVKEGCEIGFIPSPVKLE 69

Guanylate kinase;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 530412807  273 SMRPIILVGPSLKGyevTDMMQKALFDFLKHRFdgRISITRVTADISL-----------AKRSVLNNPSKHIIIERSN-T 340
Cdd:pfam00625   1 SRRPVVLSGPSGVG---KSHIKKALLSEYPDKF--GYSVPHTTRPPRKgevdgkdyyfvSKEEMERDISANEFLEYAQfS 75

                          90       100       110       120       130
                  ....*....|....*....|....*....|....*....|....*....|....*
gi 530412807  341 RSSLAEVQSEIERIFELARTlqlVALDADtINHPAQLSKTSLAPIIVYIKITSPK 395
Cdd:pfam00625  76 GNMYGTSVETIEQIHEQGKI---VILDVD-PQGVKQLRKAELSPISVFIKPPSLK 126

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 530412807   58 GSAESYTSRPSDSDVSLEEDREALRKEAERQALAQLEKAKTK 99
Cdd:pfam12052   1 GSADSNTSRPSDSDLSLEEDREALRREAERQALAQLEKAKSK 42

Src Homology 3 domain of Membrane Protein, Palmitoylated 1 (or MAGUK p55 subfamily member 1); MPP1, also called 55 kDa erythrocyte membrane protein (p55), is a ubiquitously-expressed scaffolding protein that plays roles in regulating neutrophil polarity, cell shape, hair cell development, and neural development and patterning of the retina. It was originally identified as an erythrocyte protein that stabilizes the actin cytoskeleton to the plasma membrane by forming a complex with 4.1R protein and glycophorin C. MPP1 is one of seven vertebrate homologs of the Drosophila Stardust protein, which is required in establishing cell polarity, and it contains the 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 530412807 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCE-VGFIPSP 162
Cdd:cd12080    2 MRAQFDYDPKKDNLIPCKEAGLKFQTGDIIQIINKDDSNWWQGRVEGSGEEsAGLIPSP 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 530412807 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKE-GCEVGFIPSP 162
Cdd:cd12081    2 VRAQFEYDPLKDDLIPCKQAGIRFRVGDILQIISKDDHNWWQAKLENSkNGTAGLIPSP 60

Src Homology 3 domain of Membrane Protein, Palmitoylated 6 (or MAGUK p55 subfamily member 6); MPP6, also called Veli-associated MAGUK 1 (VAM-1) or PALS2, is a scaffolding protein that binds to Veli-1, a homolog of Caenorhabditis Lin-7. It is one of seven vertebrate homologs of the Drosophila Stardust protein, which is required in establishing cell polarity, and it 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
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 530412807 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKEGCEVGFIPS 161
Cdd:cd12038    2 VKCHFDYNPYNDNLIPCKEAGLKFSKGEILQIVNREDPNWWQASHVKEGGSAGLIPS 58

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
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 530412807 105 VRTNVGYNPSPGDEvpvqgvaITFEPKDFLHIKEKYNNDWWIGRLvkEGCEVGFIPS 161
Cdd:cd00174    2 ARALYDYEAQDDDE-------LSFKKGDIITVLEKDDDGWWEGEL--NGGREGLFPA 49

Src Homology 3 domain of Membrane Protein, Palmitoylated (or MAGUK p55 subfamily member) proteins; The MPP/p55 subfamily of MAGUK (membrane-associated guanylate kinase) proteins includes at least eight vertebrate members (MPP1-7 and CASK), four Drosophila proteins (Stardust, Varicose, CASK and Skiff), and other similar proteins; they all contain one each of the core of three domains characteristic of MAGUK proteins: PDZ, SH3, and guanylate kinase (GuK). In addition, most members except for MPP1 contain N-terminal L27 domains and some also contain a Hook (Protein 4.1 Binding) motif in between the SH3 and GuK domains. CASK has an additional calmodulin-dependent kinase (CaMK)-like domain at the N-terminus. Members of this subfamily are scaffolding proteins that play important roles in regulating and establishing cell polarity, cell adhesion, and synaptic targeting and transmission, among others. 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 530412807 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVKE-GCEVGFIPSP 162
Cdd:cd11862    2 VRALFDYDPEEDPLIPCKEAGLSFKKGDILQIVNQDDPNWWQARKVGDpNGRAGLIPSQ 60

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 530412807 125 AITFEPKDFLHIKEKYNNDWWIGRLV---KEGCEVGFIPS 161
Cdd:cd12030   22 ALSFRFGDVLHVIDAGDEEWWQARRVhsdSETEEIGFIPS 61

Src Homology 3 domain of Membrane Protein, Palmitoylated 2 (or MAGUK p55 subfamily member 2); MPP2 is a scaffolding protein that interacts with the non-receptor tyrosine kinase c-Src in epithelial cells to negatively regulate its activity and morphological function. It is one of seven vertebrate homologs of the Drosophila Stardust protein, which is required in establishing cell polarity, and it 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
                 ....*....|....*....|....*....|....*....|....*....|....*..
gi 530412807 105 VRTNVGYNPSPGDEVPVQGVAITFEPKDFLHIKEKYNNDWWIGRLVkEGCEVGFIPS 161
Cdd:cd12037    2 VKCHFDYDPSSDSLIPCKEAGLKFRAGDLLQIVNQEDPNWWQACHV-EGGSAGLIPS 57

Src Homology 3 domain of Disks Large homolog 1; DLG1, also called synapse-associated protein 97 (SAP97), is a scaffolding protein that clusters at synapses and plays an important role in synaptic development and plasticity. DLG1 plays roles in regulating cell polarity, proliferation, migration, and cycle progression. It interacts with AMPA-type glutamate receptors and is critical in their maturation and delivery to synapses. It also interacts with PKCalpha and promotes wound healing. DLG1 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. DLG1 contains three PDZ domains. 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 530412807 105 VRTNVGYNPSPGDEVPVQGvaITFEPKDFLHIKEKYNNDWWIGRLVK---EGCEVGFIPSPVKLD 166
Cdd:cd12031    5 VRALFDYDKTKDSGLPSQG--LNFKFGDILHVVNASDDEWWQARQVTadgESEEIGVIPSKRRVE 67