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).
Original language | English (US) |
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Pages (from-to) | 357-363 |
Number of pages | 7 |
Journal | Pflugers Archiv European Journal of Physiology |
Volume | 433 |
Issue number | 3 |
DOIs | |
State | Published - Dec 1996 |
Keywords
- Chloride channels
- Membrane topology
- Skeletal muscle
- Sulfhydryl reagents
- Zinc ions
ASJC Scopus subject areas
- Physiology (medical)
- Physiology
- Clinical Biochemistry