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Photoactivation and dissociation of agonist molecules at the nicotinic acetylcholine receptor in voltage-clamped rat myoballs

Chabala, Lee D. and Gurney, Alison M. and Lester, Henry A. (1985) Photoactivation and dissociation of agonist molecules at the nicotinic acetylcholine receptor in voltage-clamped rat myoballs. Biophysical Journal, 48 (2). pp. 241-246. ISSN 0006-3495. PMCID PMC1329315. doi:10.1016/s0006-3495(85)83777-2. https://resolver.caltech.edu/CaltechAUTHORS:20201012-152226405

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Abstract

The photochemical properties of the azobenzene derivative, Bis-Q, were exploited to carry out an agonist concentration jump followed by a molecular rearrangement of bound agonist molecules at acetylcholine (ACh) receptor channels of voltage-clamped rat myoballs. Myoballs were bathed in solutions containing low concentrations of cis-Bis-Q, the inactive isomer. Whole-cell current relaxations were studied following a light flash that produced a concentration jump of agonist, trans-Bis-Q, followed by a second flash that produced net trans----cis photoisomerizations of Bis-Q molecules. The concentration-jump relaxation provided a measure of the mean burst duration for ACh receptor channels occupied by trans-Bis-Q (7.7 ms, 22 degrees C). The second current relaxation was a more rapid conductance decrease (phase 1, τ = 0.8 ms). Phase 1 may represent either the burst duration for receptors initially occupied by a single cis- and a single trans-Bis-Q molecule or that for unliganded receptors. Single-channel current recordings from excised outside-out membrane patches showed that single channels open following an agonist concentration jump comparable to that used in the whole-cell experiments; when many such records were averaged, a synthetic macroscopic relaxation was produced. Individual open channels closed faster following a flash that promoted trans→cis photoisomerizations of the bound ligand, thus confirming the whole-cell observations of phase 1.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/s0006-3495(85)83777-2DOIArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1329315/PubMed CentralArticle
ORCID:
AuthorORCID
Lester, Henry A.0000-0002-5470-5255
Additional Information:© 1985 The Biophysical Society. Published by Elsevier Under an Elsevier user license. Received for publication 5 November 1984 and in final form 8 April 1985. The authors would like to thank Drs. B. Sakmann, D. Corey, and R. Horn for help with techniques and Dr. R. E. Sheridan for help in setting up the equipment. The Bis-Q crystals were kindly provided by Drs. B. F. Erlanger and N. H. Wasserman; Ms. T. Stevens maintained the cultured cells. This work was supported by fellowships from the Muscular Dystrophy Association of America (L. D. Chabala) and the Del E. Webb Foundation (L. D. Chabala and A. M. Gurney), a Fulbright-Hayes travel grant (A. M. Gurney) and by United States Public Health Service grant No. NS-11756.
Funders:
Funding AgencyGrant Number
Muscular Dystrophy Association of AmericaUNSPECIFIED
Del E. Webb FoundationUNSPECIFIED
Fulbright-HayesUNSPECIFIED
NIHNS-11756
Issue or Number:2
PubMed Central ID:PMC1329315
DOI:10.1016/s0006-3495(85)83777-2
Record Number:CaltechAUTHORS:20201012-152226405
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20201012-152226405
Official Citation:L.D. Chabala, A.M. Gurney, H.A. Lester, Photoactivation and dissociation of agonist molecules at the nicotinic acetylcholine receptor in voltage-clamped rat myoballs, Biophysical Journal, Volume 48, Issue 2, 1985, Pages 241-246, ISSN 0006-3495, https://doi.org/10.1016/S0006-3495(85)83777-2.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105996
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:12 Oct 2020 22:41
Last Modified:16 Nov 2021 18:48

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