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Regulator of G-protein signaling 12 Phosphotyrosine-binding (PTB) PH-like fold RGS12 functions as a GTPase-activating protein and a transcriptional repressor. It is thought to play a role in tumorigenesis. RGS12 specifically interacts with guanine nucleotide-binding protein G(i), alpha-1 subunit and guanine nucleotide-binding protein G(k) subunit alpha. RGS proteins are multi-functional, GTPase-accelerating proteins that promote GTP hydrolysis by the alpha subunit of heterotrimeric G proteins, thereby inactivating the G protein and rapidly switching off G protein-coupled receptor signalling pathways. Upon activation by GPCRs, heterotrimeric G proteins exchange GDP for GTP, are released from the receptor, and dissociate into free, active GTP-bound alpha subunit and beta-gamma dimer, both of which activate downstream effectors. The response is terminated upon GTP hydrolysis by the alpha subunit, which can then bind the beta-gamma dimer and the receptor. RGS proteins markedly reduce the lifespan of GTP-bound alpha subunits by stabilizing the G protein transition state. PTB domains have a common PH-like fold and are found in various eukaryotic signaling molecules. This domain was initially shown to binds peptides with a NPXY motif with differing requirements for phosphorylation of the tyrosine, although more recent studies have found that some types of PTB domains can bind to peptides lack tyrosine residues altogether. In contrast to SH2 domains, which recognize phosphotyrosine and adjacent carboxy-terminal residues, PTB-domain binding specificity is conferred by residues amino-terminal to the phosphotyrosine. PTB domains are classified into three groups: phosphotyrosine-dependent Shc-like, phosphotyrosine-dependent IRS-like, and phosphotyrosine-independent Dab-like PTB domains. This cd is part of the Dab-like subgroup. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",