Xenbase is undergoing scheduled maintenance Wednesday, June 14 and Thursday, June 15, 2023. Xenbase will be unavailable on those days.

Click on this message to dismiss it.
Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
J Gen Physiol 2007 Sep 01;1303:269-81. doi: 10.1085/jgp.200709805.
Show Gene links Show Anatomy links

KCNE1 and KCNE3 stabilize and/or slow voltage sensing S4 segment of KCNQ1 channel.

Nakajo K , Kubo Y .

KCNQ1 is a voltage-dependent K(+) channel whose gating properties are dramatically altered by association with auxiliary KCNE proteins. For example, KCNE1, which is mainly expressed in heart and inner ear, markedly slows the activation kinetics of KCNQ1. Whether the voltage-sensing S4 segment moves differently in the presence of KCNE1 is not yet known, however. To address that question, we systematically introduced cysteine mutations, one at a time, into the first half of the S4 segment of human KCNQ1. A226C was found out as the most suited mutant for a methanethiosulfonate (MTS) accessibility analysis because it is located at the N-terminal end of S4 segment and its current was stable with repetitive stimuli in the absence of MTS reagent. MTS accessibility analysis revealed that the apparent second order rate constant for modification of the A226C mutant was state dependent, with faster modification during depolarization, and was 13 times slower in the presence of KCNE1 than in its absence. In the presence of KCNE3, on the other hand, the second order rate constant for modification was not state dependent, indicating that the C226 residue was always exposed to the extracellular milieu, even at the resting membrane potential. Taken together, these results suggest that KCNE1 stabilizes the S4 segment in the resting state and slows the rate of transition to the active state, while KCNE3 stabilizes the S4 segment in the active state. These results offer new insight into the mechanism of KCNQ1 channel modulation by KCNE1 and KCNE3.

PubMed ID: 17698596
PMC ID: PMC2151641
Article link: J Gen Physiol

Species referenced: Xenopus
Genes referenced: kcna2 kcne1 kcne3 kcnq1 ran

Article Images: [+] show captions
References [+] :
Abbott, MiRP1 forms IKr potassium channels with HERG and is associated with cardiac arrhythmia. 1999, Pubmed, Xenbase