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Role of the S4 segment in a voltage-dependent calcium-sensitive potassium (hSlo) channel

Authordc.contributor.authorDíaz Cuevas, Laín es_CL
Authordc.contributor.authorMeera, Pratap es_CL
Authordc.contributor.authorAmigo, Julio es_CL
Authordc.contributor.authorStefani, Enrico es_CL
Authordc.contributor.authorÁlvarez Araya, Osvaldo es_CL
Authordc.contributor.authorToro, Ligia 
Authordc.contributor.authorLatorre, Ramón es_CL
Cita de ítemdc.identifier.citationJOURNAL OF BIOLOGICAL CHEMISTRY Volume: 273 Issue: 49 Pages: 32430-32436 Published: DEC 4 1998en
Abstractdc.description.abstractWe investigated the role of individual charged residues of the S4 region of a MaxiK channel (hSlo) in channel gating, We measured macroscopic currents induced by wild type (WT) and point mutants of hSlo in inside-out membrane patches of Xenopus laevis oocytes, Of all the residues tested, only neutralizations of Arg-210 and Arg-213 were associated with a reduction in the number of gating charges as determined using the limiting slope method. Channel activation in WT and mutant channels was interpreted using an allosteric model. Mutations R207Q, R207E, and R210N facilitated channel opening in the absence of Ca2+; however, this facilitation was not observed in the channels Ca2+-bound state. Mutation R2136 behaved similarly to the WT channel in the absence of Ca2+, but Ca2+ was unable to stabilize the open state to the same extent as it does in the WT. Mutations R207Q, R207E, R210N, and R213Q reduced the coupling between Ca2+ binding and channel opening when compared with the WT. Mutations L204R, L204H, Q216R, E219Q, and E219K in the 54 domain showed a similar phenotype to the WT channel. We conclude that the S4 region in the hSlo channel is part of the voltage sensor and that only two charged amino acid residues in this region (Arg-210 and Arg-213) contribute to the gating valence of the channel.en
Keywordsdc.subjectSHAKER K+ CHANNELen
Títulodc.titleRole of the S4 segment in a voltage-dependent calcium-sensitive potassium (hSlo) channelen
Document typedc.typeArtículo de revistaen

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