Role of the S2 and S3 segment in determining the activation kinetics in Kv2.1 channels.
J Membr Biol
; 182(1): 49-59, 2001 Jul 01.
Article
em En
| MEDLINE
| ID: mdl-11426299
ABSTRACT
We constructed chimeras between the rapidly activating Kv1.2 channel and the slowly activating Kv2.1 channel in order to study to what extent sequence differences within the S1-S4 region contribute to the difference in activation kinetics. The channels were expressed in Xenopus oocytes and the currents were measured with a two-microelectrode voltage-clamp technique. Substitution of the S1-S4 region of Kv2.1 subunits by the ones of Kv1.2 resulted in chimeric channels which activated more rapidly than Kv2.1. Furthermore, activation kinetics were nearly voltage-independent in contrast to the pronounced voltage-dependent activation kinetics of both parent channels. Systematic screening of the S1-S4 region by the replacement of smaller protein parts resolved that the main functional changes generated by the S1-S4 substitution were generated by the S2 and the S3 segment. However, the effects of these segments were different The S3 substitution reduced the effective gating charge and accelerated both a voltage-dependent and a voltage-independent component of the activation time course. In contrast, the S2 substitution accelerated predominantly the voltage-dependent component of the activation time course thereby leaving the effective gating charge unchanged. It is concluded that the S2 and the S3 segment determine the activation kinetics in a specific manner.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Canais de Potássio
/
Canais de Potássio de Abertura Dependente da Tensão da Membrana
Limite:
Animals
/
Female
/
Humans
Idioma:
En
Revista:
J Membr Biol
Ano de publicação:
2001
Tipo de documento:
Article