Single-channel analysis of KCNQ K+ channels reveals the mechanism of augmentation by a cysteine-modifying reagent.

ABSTRACT: The cysteine-modifying reagent N-ethylmaleimide (NEM) is known to augment currents from native M-channels in sympathetic neurons and cloned KCNQ2 channels. As a probe for channel function, we investigated the mechanism of NEM action and subunit specificity of cloned KCNQ2-5 channels expressed in Chinese hamster ovary cells at the whole-cell and single-channel levels. Biotinylation assays and total internal reflection fluorescence microscopy indicated that NEM action is not caused by increased trafficking of channels to the membrane. At saturating voltages, whole-cell currents of KCNQ2, KCNQ4, and KCNQ5 but not KCNQ3 were augmented threefold to fourfold by 50 microm NEM, and their voltage dependencies were negatively shifted by 10-20 mV. Unitary conductances of KCNQ2 and KCNQ3 (6.2 and 8.5

SUBMITTER: Li Y 

PROVIDER: S-EPMC6729199 | biostudies-literature | 2004 Jun

REPOSITORIES: biostudies-literature