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Src homology 2 (SH2) domain found in Ras and Rab interactor 2 (RIN2)-like proteins RIN2, a member of the RIN (AKA Ras interaction/interference) family, have multifunctional domains including SH2 and proline-rich (PR) domains in the N-terminal region, and RIN-family homology (RH), VPS9 and Ras-association (RA) domains in the C-terminal region. RIN proteins function as Rab5-GEFs. Ras induces activation of Rab5 through RIN2, which is a direct downstream target of Ras and a direct upstream regulator of Rab5. In other words it is the binding of the GTP-bound form of Ras to the RA domain of RIN2 that enhances the GEF activity toward Rab5. It is thought that the RA domain negatively regulates the Rab5 GEF activity. In steady state, RIN2 is likely to form a closed conformation by an intramolecular interaction between the RA domain and the Vps9p-like (Rab5 GEF) domain, negatively regulating the Rab5 GEF activity. In the active state, the binding of Ras to the RA domain may reduce the intramolecular interaction and stabilize an open conformation of RIN2. In general SH2 domains are involved in signal transduction. They typically bind pTyr-containing ligands via two surface pockets, a pTyr and hydrophobic binding pocket, allowing proteins with SH2 domains to localize to tyrosine phosphorylated sites. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",