Regulates G protein-coupled receptor signaling cascades. Inhibits signal transduction by increasing the GTPase activity of G protein alpha subunits, thereby driving them into their inactive GDP-bound form (By similarity). It is involved in the negative regulation of the angiotensin-activated signaling pathway (By similarity). Plays a role in the regulation of blood pressure in response to signaling via G protein-coupled receptors and GNAQ. Plays a role in regulating the constriction and relaxation of vascular smooth muscle (PubMed:14608379). Binds EIF2B5 and blocks its activity, thereby inhibiting the translation of mRNA into protein (By similarity). Interacts with GNAQ. Does not interact with GNAI1 and GNAI3. Interacts with EIF2B5. Interacts with PRKG1 (isoform alpha). Expressed in a wide variety of tissues. Phosphorylated by protein kinase C. Phosphorylation by PRKG1 leads to activation of RGS2 activity. Mutant mice display increased blood pressure and impaired relaxation of vascular smooth muscle.