Binding Properties Of Acetylcholine Receptors Research Articles

Acetylcholine receptor binding properties at the rat neuromuscular junction during aging.

Specific binding characteristics of acetylcholine receptors at the diaphragm neuromuscular junction of rats aged 10 (mature adult) and 28 (aged) months were assayed by measuring 125I-alpha-bungarotoxin binding. Maximal binding to intact tissue samples was greater in the older rats; this could be attributed to an age-related increase in terminal branching. The toxin concentration at which half-maximal binding occurred increased in the older rats. Binding kinetics were assayed in finely minced tissue samples, and the association rate constant was observed to decrease in the 28-month animals. Retardation of the initial rate of toxin binding by d-tubocurarine (dTC) in minced tissue was described by a two-component nonlinear Hofstee plot; IC50 values (7.1-7.2 microM and 39.0-46.5 nM) were about the same for both age groups, but there was a significant shift toward the low-affinity values in the aged rats. Rhodamine-conjugated alpha-bungarotoxin was used to visualize receptor localization. There were no major changes in receptor distribution, and nerve terminals were consistently associated with receptors and vice versa. The data indicate a shift toward lower binding affinity during aging, which may involve changes either in one of the two toxin-binding sites on individual receptors, in dTC blocking of the channel moiety, or in receptor types.

Acetylcholine receptor binding properties and ion permeability response after covalent attachment of the local anaesthetic quinacrine

Membrane vesicles rich in nicotinic acetylcholine receptor prepared from Torpedo californica electric tissue have been irreversibly modified with quinacrine mustard, an alkylating derivative of the local anaesthetic quinacrine. The reaction blocked the ion channel regulated by the acetylcholine receptor. Acetylcholine still bound to the modified membrane vesicles with K D approx. 10 −8. The number of binding sites was reduced by up to 50%. Stopped-flow experiments showed that in contrast to what had been found with reversibly binding quinacrine no fluorescence changes caused by energy transfer from the irradiated protein to the fluorescent local anaesthetic occurred after addition of agonist. This indicates that the conformational changes associated with the activation of the ion channel are blocked by the covalent reaction with quinacrine mustard. Analysis of the membrane vesicles by SDS-polyacrylamide gel electrophoresis showed that all polypeptide chains assumed to be part of the receptor complex had reacted with the mustard. Even small components, probably lipids, migrating with the dye front, showed fluorescence.

Binding properties of acetylcholine receptors extracted from normal and from denervated rat diaphragm

FEBS LettersVolume 48, Issue 1 p. 130-132 Full-length articleFree Access Binding properties of acetylcholine receptors extracted from normal and from denervated rat diaphragm Richard Alper, Richard Alper Department of Biochemistry, State University of New York at Stony Brook, Stony Brook, N.Y. 11794, USASearch for more papers by this authorJoseph Lowy, Joseph Lowy Department of Biochemistry, State University of New York at Stony Brook, Stony Brook, N.Y. 11794, USASearch for more papers by this authorJakob Schmidt, Jakob Schmidt Department of Biochemistry, State University of New York at Stony Brook, Stony Brook, N.Y. 11794, USASearch for more papers by this author Richard Alper, Richard Alper Department of Biochemistry, State University of New York at Stony Brook, Stony Brook, N.Y. 11794, USASearch for more papers by this authorJoseph Lowy, Joseph Lowy Department of Biochemistry, State University of New York at Stony Brook, Stony Brook, N.Y. 11794, USASearch for more papers by this authorJakob Schmidt, Jakob Schmidt Department of Biochemistry, State University of New York at Stony Brook, Stony Brook, N.Y. 11794, USASearch for more papers by this author First published: November 01, 1974 https://doi.org/10.1016/0014-5793(74)81079-3Citations: 25AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume48, Issue1November 01, 1974Pages 130-132 ReferencesRelatedInformation