Downregulation of G protein-coupled receptors

Major advances have been made in understanding mechanisms mediating downreg ulation of G protein-coupled receptors. Recent studies emphasize the role o f multiple proteolytic mechanisms in downregulation. A specific mechanism o f downregulation, mediated by endocytosis of receptors via clathrin-coated pits followed by sorting to lysosomes, has been examined in detail. Specifi c protein interactions that control the specificity of G-protein-coupled re ceptor trafficking in this pathway are beginning to be elucidated.