Phosphorylation of Ion Channels: A Fundamental Regulatory Mechanism in the Control of Nerve Cell Activity
There has been much progress in recent years in our understanding of the molecular mechanisms by which neurotransmitters exert their effects on excitable cells. On the one hand, studies of the structure and function of the nicotinic acetylcholine receptor have provided a detailed picture of a directly coupled receptor/channel system, a system in which the opening of an ion channel (and transport of ions) is dependent on the continued occupation of a closely associated receptor by the transmitter. However, there are many examples of physiological responses which outlast the initial stimulus, the occupancy of the receptor by the transmitter, by seconds, minutes, or even hours. It is difficult to explain such long-lasting effects in terms of direct receptor/channel coupling, and it seems more likely that it results from some long-lasting metabolic modification of the channel. In this case the receptor and channel may not necessarily be intimately associated in a single macromolecular complex, but may be indirectly coupled via some intracellular second messenger which is produced upon occupancy of receptor by neurotransmitter.
KeywordsHydrolysis Carbohydrate Adenosine Serotonin Polyacrylamide
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