Open channel noise. I. Noise in acetylcholine receptor currents suggests conformational fluctuations.

Biophysical journal ·Vol. 47 ·No. 5 ·1985-05-00 ·Pages 709-20

Sigworth FJ

Abstract

The random passage of ions through an open channel is expected to result in shot noise fluctuations in the channel current. The patch-clamp technique now allows fluctuations of this size to be observed in single-channel currents. In the experiments reported here the acetylcholine-induced currents in cultured rat muscle cells were analyzed; fluctuations were found that were considerably larger than expected for shot noise. A low-frequency component, which was fitted with a Lorentzian, was examined in detail; it appears to arise from fluctuations in channel conductance of approximately 3% on a time scale of 1 ms. The characteristic relaxation time is voltage dependent and temperature dependent (Q10 approximately equal to 3) suggesting that the fluctuations arise from conformational fluctuations in the channel protein.

MeSH Terms

Acetylcholine/physiology Animals Calcium/physiology Diffusion Electric Conductivity Ion Channels/physiology Protein Conformation Rats Receptors, Cholinergic/physiology Sarcolemma/physiology Temperature

Chemicals

Ion Channels Receptors, Cholinergic Acetylcholine Calcium

Authors & Affiliations

1 authors, click to expand affiliations / ORCID

Sigworth F J

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30 references, click to expand

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Article Info

Journal

Biophysical journal

Abbr.

Biophys J

ISSN

0006-3495

DOI

10.1016/S0006-3495(85)83968-0

Published

1985-05-00

Pages

709-20

Language

English

Region

United States

NLM ID

0370626

PMCID

PMC1435182

Subset

External Links

PubMed source DOI: 10.1016/S0006-3495(85)83968-0 PMC Full Text View journal details

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Open channel noise. I. Noise in acetylcholine receptor currents suggests conformational fluctuations.

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