Neural regulation of properties of the nicotinic acetylcholine receptor

During nerve-muscle synapse formation, acetylcholine receptors become localized and modified to allow efficient transfer of information from nerve to muscle. In this paper we summarize our studies on two aspects of receptor modulation--their concentration at synaptic sites and their ability to desensitize in response to prolonged application of agonist. We demonstrate that receptor localization is a complex event which extensively reorganizes the structure of the junctional region. This allows the subsequent influences of contraction to be exerted differently in junctional and extrajunctional regions. We indicate that increases in muscle cell Ca2+ appear to mediate some of the effects of muscle contraction and suggest how regulation of Ca2+ levels may specify junctional and extrajunctional differences. Finally, we discuss the role of receptor phosphorylation in determining the rate of desensitization.