Beta-adrenergic receptor regulation. New insights on biochemical and molecular mechanisms

G-protein-linked transmembrane signaling is a major mechanism for processing information across biological membranes. Receptors that propagate signals from ligand binding to effector units via G-proteins are a populous class, including receptors for hormones, neurotransmitters, and autacoids. Much information has emerged on the structure of receptors, G-proteins, and effectors. Relatively little is known of the molecular basis underlying physiological regulation. The present article highlights the many recent advances that have permitted more detailed analysis of the regulation of one prominent member of the G-protein-linked receptor family, the beta-adrenergic receptor. Dynamic regulation of receptor function and expression is discussed with emphasis on the processes of desensitization and downregulation by agonist as well as up-regulation in response to steroids. Data are gleaned from studies of the biochemistry, cell, and molecular biology of beta-adrenergic receptors to provide a current model for discussion of receptor regulation.