Properties of α7-Containing Acetylcholine Receptors and Their Expression in Both Neurons and Muscle
Neurons can express a number of acetylcholine receptor genes simultaneously and assemble several receptor subtypes distinguished by subunit composition. One class of such receptors is largely extrasynaptic in location and contains the α7 gene product. It functions as a ligand-gated ion channel that is cation-selective, prefers nicotine over ACh, and rapidly desensitizes. Activation of the receptor elevates intracellular calcium levels in neurons, triggering calcium-dependent events such as neurite retraction and the release of arachidonic acid. Arachidonic acid, in turn, reversibly inhibits the receptors, suggesting negative feedback regulation. The α7 gene product is expressed not only in neurons but also in developing muscle, raising the possibility that such receptors mediate cholinergic regulation of calcium-dependent events in a variety of cells.
KeywordsArachidonic Acid Xenopus Oocyte Neurite Length Neuronal Nicotinic Acetylcholine Receptor Neurite Retraction
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