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. 2002 Feb;82(2):781–792. doi: 10.1016/S0006-3495(02)75440-4

Carboxyl tail prevents yeast K(+) channel closure: proposal of an integrated model of TOK1 gating.

Stephen H Loukin 1, Yoshiro Saimi 1
PMCID: PMC1301887  PMID: 11806920

Abstract

TOK1 encodes the channel responsible for the prominent outward K(+) current of the yeast plasma membrane. It can dwell in several impermeable states, including a rapidly transiting, K(+)-electromotive-force-dependent "R" (rectifying) state, a voltage-independent "IB" (interburst) state, and a set of [K(+)](ext) and voltage-dependent "C" (closed) states. Whereas evidence suggests that the C states result from the constriction of an inner gate at the cytosolic end of the pore, R is most likely an intrinsic gating property of the K(+) filter. Here, we present evidence that Tok1's carboxyl-tail domain also plays an intimate role in channel gating by dynamically preventing inner-gate closures. We present an integrated model of TOK1 gating in which the filter gate, inner gate, and carboxyl tail interact to produce the various phenomenological states. Both wild-type and tailless behaviors can be replicated using Monte Carlo computer simulations based on this model.

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Selected References

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