Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Charge displacements in a single potassium ion channel macromolecule during gating.
Mika YH
,
Palti Y
.
???displayArticle.abstract???
Single ion channel currents can only provide indirect information on channel molecular events (except for timing). In contrast, the electric displacement currents associated with channel gating, termed gating currents, can provide direct information regarding the channel molecule's conformational changes. However, thus far gating currents have been measured only from ensembles of numerous stochastically activated channels and therefore the information they provide is limited. This work presents, for the first time, measurements of gating currents from a single channel molecule. Averaging close to 8000 pre-open currents, aligned to the single channel opening time, enabled the detection of single channel gating currents with a resolution of 2 electron charges. The measured charge displacements show: 1) a slow component, approximately 2 fA above baseline level, assumed to represent stochastic conformational changes, and 2) transients, the most significant of which occur 1.1 and 0.3 ms before channel opening. The transients most likely represent apparent deterministic stages in the gating process. The largest transient current peak was 5.1 +/- 1.6 fA and the total equivalent charge transported across the membrane was 4.7 +/- 2.5 electron charges. This data is unique also in that it presents monitoring of the behavior of a single, well-defined macromolecule.
Almers,
Gating currents and charge movements in excitable membranes.
1978, Pubmed
Almers,
Gating currents and charge movements in excitable membranes.
1978,
Pubmed
Armstrong,
Currents related to movement of the gating particles of the sodium channels.
1973,
Pubmed
Armstrong,
Sodium channels and gating currents.
1981,
Pubmed
Bezanilla,
Molecular basis of gating charge immobilization in Shaker potassium channels.
1991,
Pubmed
,
Xenbase
Conti,
Quantal charge redistributions accompanying the structural transitions of sodium channels.
1989,
Pubmed
,
Xenbase
Crouzy,
Fluctuations in ion channel gating currents. Analysis of nonstationary shot noise.
1993,
Pubmed
HODGKIN,
A quantitative description of membrane current and its application to conduction and excitation in nerve.
1952,
Pubmed
Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed
Iverson,
A-type potassium channels expressed from Shaker locus cDNA.
1988,
Pubmed
,
Xenbase
Kamb,
Molecular characterization of Shaker, a Drosophila gene that encodes a potassium channel.
1987,
Pubmed
Keynes,
Kinetics and steady-state properties of the charged system controlling sodium conductance in the squid giant axon.
1974,
Pubmed
Neher,
Single-channel currents recorded from membrane of denervated frog muscle fibres.
1976,
Pubmed
Perozo,
Gating currents in Shaker K+ channels. Implications for activation and inactivation models.
1992,
Pubmed
,
Xenbase
Schoppa,
The size of gating charge in wild-type and mutant Shaker potassium channels.
1992,
Pubmed
Sigworth,
Open channel noise. I. Noise in acetylcholine receptor currents suggests conformational fluctuations.
1985,
Pubmed
Stühmer,
Gating currents of inactivating and non-inactivating potassium channels expressed in Xenopus oocytes.
1991,
Pubmed
,
Xenbase
Stühmer,
Electrophysiological recording from Xenopus oocytes.
1992,
Pubmed
,
Xenbase
Zagotta,
Gating of single Shaker potassium channels in Drosophila muscle and in Xenopus oocytes injected with Shaker mRNA.
1989,
Pubmed
,
Xenbase