G-Protein-coupled Receptors: Regulatory Role of Receptor Kinases and Arrestin Proteins

Receptors that couple to guanine nucleotide regulatory proteins comprise an extraordinarily diverse collection of functional entities. They mediate responses to stimuli as varied as neurotransmitters, hormones, chemoattractants, cytokines, odorants, and even photons of light (Dohlman et al. 1991). It has become increasingly clear that the functional and regulatory properties of these receptors are remarkably conserved, mirroring the substantial conservation of their structure and topographical features. Activation of such receptors with agonists or other stimuli leads to conformational changes that render the receptors "active." At least two major pathways exist along which the activated receptors may proceed. One pathway involves interaction with G protein, activation of a biochemical effector, and generation of a physiological response. The other pathway involves interaction with proteins other than the G proteins, leading to other fates not involving activation of physiological responses. Perhaps the best-studied of such pathways is that by which the activated receptors interact...