Homomeric and native alpha 7 acetylcholine receptors exhibit remarkably similar but non-identical pharmacological properties, suggesting that the native receptor is a heteromeric protein complex.
Sucrose gradient analysis of chick acetylcholine receptor (AChR) alpha 7 subunits expressed in oocytes indicates that they form pharmacologically active homomers of the same size as native alpha 7 AChRs, a size compatible with a complex of five alpha 7 subunits. By immunoisolating the [35S]methionine-labeled alpha 7 subunits we also demonstrate that they do not appear to assemble with endogenous Xenopus AChR subunits. Pharmacological characterization of detergent-solubilized brain alpha 7 AChRs and alpha 7 homomers reveals that they have similar but nonidentical properties. The pharmacological difference is most accentuated for cytisine (approximately 50-fold). Thus, at least in E18 chicken brain, most or all of the native alpha 7 AChRs do not appear to be homomeric.
Anand
R
R
Department of Neuroscience, University of Pennsylvania, Philadelphia 19104-607.
Peng
X
X
Lindstrom
J
J
D000818:Animals; D000911:Antibodies, Monoclonal; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism; D001923:Brain Chemistry; D002038:Bungarotoxins / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D002645:Chickens; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression; D009865:Oocytes / Q000378:metabolism; D011950:Receptors, Cholinergic / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014981:Xenopus
D000911:Antibodies, Monoclonal; D002038:Bungarotoxins; D011950:Receptors, Cholinergic