Referenced in: none

Automatically associated channels: ClC1 , ClC4

Title: Probing the major skeletal muscle chloride channel with Zn2+ and other sulfhydryl-reactive compounds.

Authors: L Kürz, S Wagner, A L George, R Rüdel

Journal, date & volume: Pflugers Arch., 1997 Jan , 433, 357-63

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/9064653

Abstract
The sensitivity of the human skeletal muscle Cl- channel, hClC-1, towards various sulfhydryl-reactive agents was tested with the channel expressed in Xenopus oocytes and in human embryonic kidney cells. External but not internal Zn2+, at 1 mM, substantially reduced the current without affecting activation parameters. External Cd2+ and Hg2+ as well as organic mercurial compounds reduced the Cl- currents to a similar degree. With the mutant channel hClC-1 D136G, presumed to have a defective voltage sensor, external Zn2+ also reduced the current without effect on the altered gating. These findings suggest that hClC-1 contains cysteine residues near the extracellular face that may directly influence ion conduction. Since Zn2+ can also bind to histidine side chains, we tested the effect of compounds with either more cysteine- or more histidine-specificity. The results confirm the involvement of cysteine(s) in the observed effects but do not exclude the involvement of histidine(s).