Linked Life Data

8786350

Source:http://linkedlifedata.com/resource/pubmed/id/8786350

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1996-9-26
pubmed:abstractText
Voltage-dependent Na+ channels are thought to sense membrane potential with fixed charges located within the membrane's electrical field. Measurement of open probability (Po) as a function of membrane potential gives a quantitative indication of the number of such charges that move through the field in opening the channel. We have used single-channel recording to measure skeletal muscle Na+ channel open probability at its most negative extreme, where channels may open as seldom as once per minute. To prevent fast inactivation from masking the voltage dependence of Po, we have generated a clone of the rat skeletal muscle Na+ channel that is lacking in fast inactivation (IFM1303QQQ). Using this mutant channel expressed in Xenopus oocytes, and the extra resolution afforded by single-channel analysis, we have extended the resolution of the hyperpolarized tail of the Po curve by four orders of magnitude. We show that previous measurements, which indicated a minimum of six effective gating charges, may have been made in a range of Po values that had not yet arrived at its limiting slope. In our preparation, a minimum of 12 charges must function in the activation gating of the channel. Our results will require reevaluation of kinetic models based on six charges, and they have major implications for the interpretation of S4 mutagenesis studies and structure/function models of the Na+ channel.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0022-1295
pubmed:author
pubmed:issnType
Print
pubmed:volume
106
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1053-68
pubmed:dateRevised
2008-11-20
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Transfer of twelve charges is needed to open skeletal muscle Na+ channels.
pubmed:affiliation
Department of Molecular Physiology and Biophysics, University of Vermont, Colchester 05446, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't