R7BP

R7BP is a small, membrane-associated protein that serves as a binding partner and membrane anchor for the R7 family of regulator of G protein signaling (RGS) proteins. In vertebrates, R7BP binds to R7 RGS proteins—RGS6, RGS7, RGS9, and RGS11—and to the G protein β subunit Gβ5, forming a trimeric complex that localizes to cellular membranes. This membrane targeting is important for the proper function of the R7–Gβ5 complexes in regulating G protein–coupled receptor (GPCR) signaling.

The association of R7BP with R7 RGS proteins is mediated in part by the DEP domain-containing region of the R7 proteins and by palmitoylation events on R7BP itself. The N-terminus of R7BP contains lipid modification motifs that drive membrane attachment, enabling the complex to reside at the plasma membrane and intracellular membranes where GPCR signaling occurs. By anchoring the R7 RGS–Gβ5 complex to membranes, R7BP influences the stability, localization, and regulatory activity of these GAPs, thereby shaping the duration and intensity of GPCR signaling in neurons.

R7BP is predominantly expressed in brain tissue and retina, aligning with the cellular distribution of R7 RGS proteins and Gβ5. Its function is considered to be modulatory rather than catalytic, providing spatial regulation of R7 RGS–Gβ5–mediated signaling. In the retina and certain brain circuits, analogous membrane-anchoring proteins help position G protein signaling complexes to meet local signaling demands, a role that R7BP fulfills for the R7 RGS family.

See also: R9AP, RGS7, Gβ5, GPCR signaling.