Linked Life Data

11689945

Source:http://linkedlifedata.com/resource/pubmed/id/11689945

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6859
pubmed:dateCreated
2001-11-5
pubmed:abstractText
K+ channels are transmembrane proteins that are essential for the transmission of nerve impulses. The ability of these proteins to conduct K+ ions at levels near the limit of diffusion is traditionally described in terms of concerted mechanisms in which ion-channel attraction and ion-ion repulsion have compensating effects, as several ions are moving simultaneously in single file through the narrow pore. The efficiency of such a mechanism, however, relies on a delicate energy balance-the strong ion-channel attraction must be perfectly counterbalanced by the electrostatic ion-ion repulsion. To elucidate the mechanism of ion conduction at the atomic level, we performed molecular dynamics free energy simulations on the basis of the X-ray structure of the KcsA K+ channel. Here we find that ion conduction involves transitions between two main states, with two and three K+ ions occupying the selectivity filter, respectively; this process is reminiscent of the 'knock-on' mechanism proposed by Hodgkin and Keynes in 1955. The largest free energy barrier is on the order of 2-3 kcal mol-1, implying that the process of ion conduction is limited by diffusion. Ion-ion repulsion, although essential for rapid conduction, is shown to act only at very short distances. The calculations show also that the rapidly conducting pore is selective.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0028-0836
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
414
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
73-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Energetics of ion conduction through the K+ channel.
pubmed:affiliation
Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10021, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't