The Biochemical Properties and Regulation of Acetylcholine Receptors in Normal and Denervated Muscle (original) (raw)

1. Jeremy P. Brookes,
2. Darwin K. Berg†, and
3. Zach W. Hall
4. Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115

Excerpt

Mammalian skeletal muscle fibers have two populations of acetylcholine receptors that are distinguished by their location on the fiber surface and by their independent modes of regulation. One population, which binds the acetylcholine released by nerve terminals and thus mediates neuromuscular transmission, occurs in the folds of muscle membrane immediately underlying the nerve terminals (Porter et al. 1973; Fertuck and Salpeter 1974; Daniels and Vogel 1975). It is not known when these receptors first appear during development, but in the adult, their number appears to be relatively constant and is little affected by denervation or by muscle activity (Frank et al. 1975).

Another population of ACh receptors occurs in the muscle membrane outside the junction. In contrast to junctional receptors, the level of extrajunctional receptors is capable of wide variation. In normal adult muscle, the number of these receptors is very low, but in denervated muscle, and in some muscles...

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  ↵* Present address: MRC Neuroimmunology Project, Department of Zoology, University College, London WC1E 6BT, England
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  ↵† Present address: Department of Biology, University of California at San Diego, La Jolla, California 92037.