Linked Life Data

6255062

Source:http://linkedlifedata.com/resource/pubmed/id/6255062

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1981-2-24
pubmed:abstractText
The open-channel conductance properties of a voltage-gated channel from sarcoplasmic reticulum were studied in planar phospholipid membranes. The channel is ideally selective for K+ over Cl- and for K+ over Ca++. In symmetrical 1 M solutions, the single-channel conductance (in pmho) falls in the order: K+ (214) > NH4+ (157) > Rb+ (125) > Na+ (72) > La+ (8.1) > Cs+ (< 3). In neutral bilayers, the channel conductance saturates with ion activity according to a rectangular hyperbolic relation, with half-saturation activities of 54 mM for K+ and 34 mM for Na+. Under symmetrical salt conditions, the K+:Na+ channel conductance ratio increases with salt activity, but the permeability ratio, measured by single-channel bi-ionic potentials, is constant between 20 mM and 2.5 M salt; the permeability ratio is equal to the conductance ratio in the limit of low-salt concentration. The channel conductance varies < 5% in the voltage range -100 to +70 mV. The maximum conductance varies K+ and Na+ is only weakly temperature dependent (delta H++ = 4.6 and 5.3 kcal/mol, respectively), but that of Li+ varies strongly with temperature (delta H++ = 13 kcal/mol). The channel's K+ conductance is blocked asymmetrically by Cs+, and this block is competitive with K+. The results are consistent with an Eyring-type barriers as it permeates the channel. The data conform to Lüger's (1973. Biochem. Biophys. Acta. 311:423-441) predictions for a "pure" single-ion channel.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0022-1295
pubmed:author
pubmed:issnType
Print
pubmed:volume
76
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
425-46
pubmed:dateRevised
2008-11-20
pubmed:meshHeading
pubmed:year
1980
pubmed:articleTitle
Ionic selectivity, saturation, and block in a K+-selective channel from sarcoplasmic reticulum.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S.