Coassembly of K sub V LQT1 and minK (IsK) proteins to form cardiac I sub Ks potassium channel.
Sanguinetti, M. C.; Curran, M. E.; Zou, A.; Shen, J.; Spector, P. S.; Atkinson, D. L.; Keating, M. T.
[Letter] Nature. 384(6604):80-83, November 7, 1996.

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The slowly activating delayed-rectifier K sup current, IKs, modulates the repolarization of cardiac action potentials. The molecular structure of the IKs channel is not known, but physiological data indicate that one component of the IKs is minK [1-6], a 130-amino-acid protein with a single putative transmembrane domain [7]. The size and structure of this protein is such that it is unlikely that minK alone forms functional channels [8,9]. We have previously used positional cloning techniques to define a new putative K sup -channel gene, KVLQT1 [10]. Mutations in this gene cause long-QT syndrome, an inherited disorder that increases the risk of sudden death from cardiac arrhythmias. Here we show that KVLQT1 encodes a K sup channel with biophysical properties unlike other known cardiac currents. We considered that KV LQT1 might coassemble with another subunit to form functional channels in cardiac myocytes. Coexpression of KV LQT1 with minK induced a current that was almost identical to cardiac IKs. Therefore, KV LQT1 is the subunit that coassembles with minK to form IKs channels and IKs dysfunction is a cause of cardiac arrhythmia.

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