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Biophys J. 1992 Nov;63(5):1406-11.

Tandem linkage of Shaker K+ channel subunits does not ensure the stoichiometry of expressed channels.

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  • 1Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510.

Abstract

Shaker K+ channels are multimeric, probably tetrameric proteins. Substitution of a conserved leucine residue to valine (V2) at position 370 in the Drosophila Shaker 29-4 sequence results in large alterations in the voltage dependence of gating in the expressed channels. In order to determine the effects of this mutation in hybrid channels with a fixed stoichiometry of V2 and wild-type (WT) subunits we generated cDNA constructs of two linked-monomeric subunits similar to the tandem constructs previously reported by Isacoff, E. Y., Y. N. Jan, and L. Y. Jan. (1990. Nature (Lond.). 345:530-534). In addition, we constructed a tandem cDNA containing a wild-type subunit and a truncated nonfunctional subunit (Sh102) that suppresses channel expression. We report that the voltage-dependence of the channels produced with WT and V2 subunits varied significantly with the order of the subunits in the construct (WT-V2 or V2-WT), while the WT-Sh102 construct yielded currents that were much larger than expected. These results suggest that the tandem linkage of Shaker subunits does not guarantee the stoichiometry of the expressed channel proteins.

PMID:
1477286
PMCID:
PMC1261445
DOI:
10.1016/S0006-3495(92)81703-4
[PubMed - indexed for MEDLINE]
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