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Affinity labelling of neuronal acetylcholine receptors localizes acetylcholine‐binding sites to their β‐subunits
Author(s) -
Whiting Paul,
Lindstrom Jon
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81464-3
Subject(s) - acetylcholine receptor , nicotinic agonist , acetylcholine , dithiothreitol , torpedo , protein subunit , biochemistry , nicotinic acetylcholine receptor , receptor , neuromuscular junction , chemistry , biology , neuroscience , gene , endocrinology , enzyme
Neuronal nicotinic acetylcholine receptors (AChRs) from brains of chickens and rats consist of two types of subunits, α and β, of which a shares some antigenic determinants with α‐subunits from AChRs of electric organ and muscle [(1986) Biochemistry 25, 2082‐2093; (1986) J. Neurosci. G, 3061‐3069; (1986) Proc. Natl. Acad. Sci. USA, in press]. Here we demonstrate that after reduction with dithiothreitol (DTT) the AChRs can be specifically labelled with the acetylcholine‐binding site directed reagent 4‐( N ‐maleimido)benzyltri [ 3 H]methylammonium iodide. Labelling of the β‐subunits of neuronal nicotinic AChRs indicates that the acetylcholine‐binding site, and amino acids which may be homologous to Cys 192–193 of the α‐subunits of AChRs from electric organ and muscle, are located on the β‐subunit of neuronal AChRs. These results suggest that although neuronal nicotinic AChRs have some structural homologies to AChRs from muscle and electric organs, the AChRs from these sources are quite distant relatives in an extended gene family.