Regulation of G protein-coupled receptors by receptor kinases and arrestins

This chapter discusses the regulation of G protein-coupled receptors by receptor kinases and arrestins. Signal transduction through seven-transmembrane domain or serpentine receptors, which is mediated by guanine nucleotide-binding (G) proteins, accounts for a significant fraction of all signaling in the body. Heterotrimeric G proteins modulate the activities of multiple effectors, including cyclic GMP (cGMP) phosphodiesterase, adenylyl cyclase, phospholipases C and A2, and potassium and calcium ion channels, which alter the levels of second messenger molecules and ultimately lead to a variety of cell-specific events. Absorption of a photon of light by a molecule of rhodopsin residing in the disk membrane of rod outer segments results in the isomerization of the chromophore 11-cis-retinal to the all-trans conformation, yielding the active form of rhodopsin, metarhodopsin II. Two members of the G protein-coupled receptor kinases family appear to be expressed in a limited number of tissues. It is found that rhodopsin kinase is predominantly expressed in the retina, where it localizes to both rod and cones by immunofluorescence, and in the pineal body to a lesser extent. © 1995 Academic Press Inc.