Pflugers Arch 1998 Dec 01;4371:172-4. doi: 10.1007/s004240050765.

Increase of the single-channel conductance of KvLQT1 potassium channels induced by the association with minK.

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Gating of the delayed rectifier K+ channel KvLQT1 is drastically slowed by the association with the small membrane protein minK and it is thought that the KvLQT1/minK complex underlies the slow delayed rectifier K+ current of cardiac cells. There is controversy about the effects of the association between KvLQT1 and minK on the single-channel conductance. Here, nonstationary fluctuation analysis was applied to inward K+ tail currents recorded with a high-time resolution (5 kHz bandwidth) from macropatches of homomeric KvLQT1 and heteromeric KvLQT1/minK channels expressed in Xenopus oocytes to estimate their single-channel conductance. It was found that heteromers have a threefold larger conductance (5.8 pS) compared to homomeric channels (1.8 pS) in symmetrical high-K+ solutions. The larger conductance of heteromers explains in part their larger macroscopic conductance in heterologous expression systems. The molecular mechanism underlying the conductance increase remains to be identified.

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Species referenced: Xenopus
Genes referenced: arfgap1 kcne1 mink1