In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 98, No. 17 ( 2001-08-14), p. 9617-9623
Abstract:
Upon depolarization positive charges contained in the transmembrane
segment S4 of voltage-dependent channels are displaced from the cytoplasmic to the external milieu. This charge movement leads to
channel opening. In Shaker K + channels four
positively charged arginines in the S4 domain are transferred from the internal to the external side of the channel during activation. The
distance traveled by the S4 segment during activation is unknown, but large movements should be constrained by the S3–S4 linker.
Constructing deletion mutants, we show that the activation time constant and the midpoint of the voltage activation curve of the Shaker K + channel macroscopic currents
becomes a periodic function of the S3–S4 linker length for linkers shorter than 7 aa residues. The periodicity is that typical of
α-helices. Moreover, a linker containing only 3 aa is enough to recover the wild-type phenotype. The deletion method revealed the
importance of the S3–S4 linker in determining the channel gating kinetics and indicated that the α-helical nature of S4 extends toward
its N terminus. These results support the notion that a small displacement of the S4 segment suffices to displace the four gating
charges involved in channel opening.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.171306298
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2001
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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