G-protein-linked transmembrane signaling has emerged as a major pathway for information transduction across the cell membrane. 2. In addition to photopigments that propagate the signal from light, cell-surface receptors for hormones, neurotransmitters, and autacoids propagate signals from ligand binding to membrane-bound effector units via G-proteins. 3. Biochemical and molecular features of one prominent member of these receptors, the beta-adrenergic receptor, will be highlighted in the present article. 4. The role of the human epidermoid carcinoma A431 cells as a model for the study of the structure and biology of beta-adrenergic receptors will be emphasized. 5. A model for receptor regulation, gleaned from recent advances in the biochemistry, cell and molecular biology of beta-adrenergic receptors, is discussed.
