Electrokinetics of miniature K+ channel: open-state V sensitivity and inhibition by K+ driving force.
J Membr Biol
; 214(1): 9-17, 2006.
Article
em En
| MEDLINE
| ID: mdl-17568981
ABSTRACT
Kcv, isolated from a Chlorella virus, is the smallest known K+ channel. When Kcv is expressed in Xenopus oocytes and exposed to 50 mM [K+](o), its open-state current-voltage relationship (I-V) has the shape of a "tilted S" between -200 and +120 mV. Details of this shape depend on the conditioning voltage (V (c)) immediately before an I-V recording. Unexpectedly, the I-V relationships, recorded in different [K+](o), do intersect. These characteristics are numerically described here by fits of a kinetic model to the experimental data. In this model, the V (c) sensitivity of I-V is mainly assigned to an affinity increase of external K+ association at more positive voltages. The general, tilted-S shape as well as the unexpected intersections of the I-V relationships are kinetically described by a decrease of the cord conductance by the electrochemical driving force for K+ in either direction, like in fast V-dependent blocking by competing ions.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Potássio
/
Proteínas Virais
/
Canais de Potássio
/
Phycodnaviridae
/
Potenciais da Membrana
/
Modelos Biológicos
Tipo de estudo:
Diagnostic_studies
/
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
J Membr Biol
Ano de publicação:
2006
Tipo de documento:
Article