Abstract
The inactivation of the C1C-0 chloride channel is very temperature sensitive and is greatly facilitated by the binding of a zinc ion (Zn2+) from the extracellular side, leading to a Zn2+-induced current inhibition. To further explore the relation of Zn2+ inhibition and the C1C-0 inactivation, we mutated all 12 cysteine amino acids in the channel and assayed the effect of Zn2+ on these mutants. With this approach, we found that C212 appears to be important for the sensitivity of the Zn2+ inhibition. Upon mutating C212 to serine or alanine, the inactivation of the channel in macroscopic current recordings disappears and the channel does not show detectable inactivation events at the single-channel level. At the same time, the channel's sensitivity to Zn2+ inhibition is also greatly reduced. The other two cysteine mutants, C213G and C480S, as well as a previously identified mutant, S123T, also affect the inactivation of the channel to some degree, but the temperature-dependent inactivation process is still present, likewise the high sensitivity of the Zn2+ inhibition. These results further support the assertion that the inhibition of Zn2+ on C1C-0 is indeed due to an effect on the inactivation of the channel. The absence of inactivation in C212S mutants may provide a better defined system to study the fast gating and the ion permeation of C1C-0.
Original language | English (US) |
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Pages (from-to) | 1-12 |
Number of pages | 12 |
Journal | Journal of General Physiology |
Volume | 114 |
Issue number | 1 |
State | Published - Jul 1999 |
Externally published | Yes |
Keywords
- C1C-0
- Cysteine mutagenesis
- Slow gating
- Zn inhibition
ASJC Scopus subject areas
- Physiology