Regulation Of Receptor Function

This chapter summarizes the phosphorylation of several important plasma membrane receptors: the β-adrenergic receptor coupled to adenylate cyclase; rhodopsin, the archetypal “light” receptor of the rod outer segment; the nicotinic cholinergic receptor; the IgE receptor; and the transferrin receptor. Several cell surface receptors that possess tyrosine kinase activity are also briefly discussed in the chapter. The β-adrenergic receptor is a ubiquitous plasma membrane glycoprotein that mediates catecholamine stimulation of the enzyme adenylate cyclase. One of the striking features of the β-adrenergic receptor-adenylate cyclase system is that prolonged incubation of catecholamines with a cell leads to a diminution or blunting of the response to further challenge by the agonist. This process, termed as “desensitization,” leads to reduced cAMP levels in the cell and consequently to a reduced cellular response to the hormone. In “homologous desensitization,” exposure to a pagonist leads to diminished responsiveness only to subsequent stimulation by pagonists. In “heterologous desensitization,” a more general blunting of responsiveness to other hormonal activators is also observed. © 1987, Academic Press Inc.

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Author Robert J. Lefkowitz Medicine, Cardiology