Journal of Biological Chemistry
Volume 271, Issue 45, 8 November 1996, Pages 28311-28317
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Membranes and Bioenergetics
Comparison of Binding and Block Produced by Alternatively Spliced Kvβ1 Subunits*

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Voltage-gated K+ (Kv) channels consist of α subunits complexed with cytoplasmic Kvβ subunits. Kvβ1 subunits enhance the inactivation of currents expressed by the Kv1 α subunit subfamily. Binding has been demonstrated between the C terminus of Kvβ1.1 and a conserved segment of the N terminus of Kv1.4, Kv1.5, and Shaker α subunits. Here we have examined the interaction and functional properties of two alternatively spliced human Kvβ subunits, 1.2 and 1.3, with Kvα subunits 1.1, 1.2, 1.4, and 1.5. In the yeast two-hybrid assay, we found that both Kvβ subunits interact specifically through their conserved C-terminal domains with the N termini of each Kvα subunit. In functional experiments, we found differences in modulation of Kv1α subunit currents that we attribute to the unique N-terminal domains of the two Kvβ subunits. Both Kvβ subunits act as open channel blockers at physiological membrane potentials, but hKvβ1.2 is a more potent blocker than hKvβ1.3 of Kv1.1, Kv1.2, Kv1.4, and Kv1.5. Moreover, hKvβ1.2 is sensitive to redox conditions, whereas hKvβ1.3 is not. We suggest that different Kvβ subunits extend the range over which distinct Kv1α subunits are modulated and may provide a variable mechanism for adjusting K+ currents in response to alterations in cellular conditions.

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*

This work was supported by grants from the American Heart Association, Northeast Ohio Affiliate (to B. A. W.), National Institutes of Health Grants NS23877 and HL36030 (to A. M. B.), Deutsche Forschungsgemeinschaft (to J. K.), and Medical Research Council of Canada (to Z. W.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.