RGS13 is a member of R4 subfamily of RGS family, a diverse group of multifunctional proteins that regulate cellular signaling events downstream of G-protein coupled receptors (GPCRs) []. Signaling is initiated when GPCRs bind to their ligands, triggering the replacement of GDP bound to the G-alpha subunits of heterotrimeric G proteins with GTP. RGSs inhibit signal transduction by increasing the GTPase activity of G protein alpha subunits, thereby driving them into their inactive GDP-bound form. This activity defines them as GTPase activating proteins (GAPs).RGS13 exhibits relatively restricted tissue expression in T and B lymphocytes, as well as mast cells (MCs). RGS13 acts together with RGS1 to regulate chemokine receptor signaling in germinal centre B lymphocytes [, ]. In MCs, it inhibits G protein-coupled receptor signaling and suppresses IgE-antigen-induced MC degranulation and anaphylaxis [].
