title: Properties of embryonic and adult muscle acetylcholine receptors transiently expressed in COS cells.
abstract: We used transient transfection in COS cells to compare the properties of mouse muscle acetylcholine receptors (AChRs) containing alpha, beta, delta, and either gamma or epsilon subunits. gamma- and epsilon-AChRs had identical association rates for binding 125I-alpha-bungarotoxin, and identical curves for inhibition of toxin binding by d-tubocurarine, but epsilon-AChRs had a significantly longer half-time of turnover in the membrane than gamma-AChRs. A myasthenic serum specific for the embryonic form of the AChR reduced toxin binding to gamma-, but not epsilon-AChRs. The gamma-AChRs had channel characteristics of embryonic AChRs, whereas the major class of epsilon-AChR channels had the characteristics of adult AChRs. Two minor channel classes with smaller conductances were also seen with epsilon-AChR. Thus, some, but not all, of the differences between AChRs at adult endplates and those in the extrasynaptic membrane can be explained by the difference in subunit composition of gamma- and epsilon-AChRs.
authors.affiliation: Department of Physiology, University of California, San Francisco 94143-0444.
authors.forename: Y
authors.initials: Y
authors.lastname: Gu
authors.forename: A
authors.initials: A
authors.lastname: Franco
authors.forename: P D
authors.initials: PD
authors.lastname: Gardner
authors.forename: J B
authors.initials: JB
authors.lastname: Lansman
authors.forename: J R
authors.initials: JR
authors.lastname: Forsayeth
authors.forename: Z W
authors.initials: ZW
authors.lastname: Hall
mesh_terms: D000818:Animals; D001665:Binding Sites; D002038:Bungarotoxins / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D004553:Electric Conductivity; D015870:Gene Expression; D007700:Kinetics; D051379:Mice; D009132:Muscles / Q000196:embryology / Q000378:metabolism*; D011233:Precipitin Tests; D011950:Receptors, Cholinergic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014162:Transfection; D014403:Tubocurarine / Q000378:metabolism / Q000494:pharmacology
chemical_list: D002038:Bungarotoxins; D011950:Receptors, Cholinergic; D014403:Tubocurarine