Regulation of Antagonist and Agonist Binding to the Muscarinic Acetylcholine Receptor by Protein Phosphorylation

Abstract

The mechanisms by which receptors for neurotransmitters and hormones are regulated are largely unknown. Recently, however, I have suggested that muscarinic cholinergic receptors of rat brain synaptic membranes may be regulated by a protein phosphorylation mechanism (Burgoyne, 1980, 1981). This suggestion stemmed from the two observations. First, that incubation of synaptic membranes under protein phosphorylating conditions led to a calmodulin-dependent, cAMP-stimulated loss in ³H-QNB binding. Second, that exposure of primary cultures of rat cerebellum to the agonist carbachol led to an increase in membrane protein phosphorylation concomitant with agonistinduced receptor loss.