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Titolo:
SELECTIVITY CHANGES DURING ACTIVATION OF MUTANT SHAKER POTASSIUM CHANNELS
Autore:
ZHENG J; SIGWORTH FJ;
Indirizzi:
YALE UNIV,SCH MED,DEPT CELLULAR & MOL PHYSIOL,333 CEDAR ST NEW HAVEN CT 06520 YALE UNIV,SCH MED,DEPT CELLULAR & MOL PHYSIOL NEW HAVEN CT 06520
Titolo Testata:
The Journal of general physiology
fascicolo: 2, volume: 110, anno: 1997,
pagine: 101 - 117
SICI:
0022-1295(1997)110:2<101:SCDAOM>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
INTERNAL TEA BLOCKADE; K+ CHANNEL; GATING CURRENTS; XENOPUS OOCYTES; SODIUM-CHANNEL; BINDING-SITE; ION CHANNELS; PORE; MUTATIONS; TRANSITIONS;
Keywords:
ION CHANNEL GATING; CONSERVED SEQUENCE; POINT MUTATION; PATCH CLAMP; MUTAGENESIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
45
Recensione:
Indirizzi per estratti:
Citazione:
J. Zheng e F.J. Sigworth, "SELECTIVITY CHANGES DURING ACTIVATION OF MUTANT SHAKER POTASSIUM CHANNELS", The Journal of general physiology, 110(2), 1997, pp. 101-117

Abstract

Mutations of the pore-region residue T442 in Shaker channels result in large effects on channel kinetics. We studied mutations at this position in the backgrounds of NH2-terminal-truncated Shaker H4 and a Shaker-NGK2 chimeric channel having high conductance (Lopez, G.A, Y.N. Jan, and L.Y. Jan. 1994. Nature (Lond.). 367: 179-182). While mutations of T442 to C, D, H, V, or Y resulted in undetectable expression in Xenopus oocytes, S and G mutants yielded functional channels having deactivation time constants and channel open times two to three orders of magnitude longer than those of the parental channel. Activation time courses at depolarized potentials were unaffected by the mutations, as were first-latency distributions in the T442S chimeric channel. The mutant channels show two subconductance levels, 37 and 70% of full conductance. From single-channel analysis, we concluded that channels always pass through tile larger subconductance state on the way to and from the open state. The smaller subconductance state is traversed in similar to 40% of activation time courses. These states apparently representkinetic intermediates in channel gating having voltage-dependent transitions with apparent charge movements of similar to 1.6e(0). The fully open T442S chimeric channel has the conductance sequence Rb+ > NH4+ > K+. The opposite conductance sequence, K+ > NH4+ > Rb+, is observed in each of the subconductance states, with the smaller subconductance state discriminating most strongly against Rb+.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 23/09/20 alle ore 10:25:00