Molecular basis of IsK protein regulation by oxidation or chelation

Slowly activating IsK channels were expressed in Xenopus oocytes and exposed to oxidative agents. Oxidative treatment reduced the resulting current IsK, while no inhibition was observed for IsK protein mutants carrying a Ser mutation instead of a highly conserved Cys residue in the intracellular dom...

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Bibliographic Details
Published in:The Journal of biological chemistry 1995-02, Vol.270 (8), p.3638
Main Authors: Busch, A E, Waldegger, S, Herzer, T, Raber, G, Gulbins, E, Takumi, T, Moriyoshi, K, Nakanishi, S, Lang, F
Format: Article
Language:English
Subjects:
Animals
Chelating Agents
Humans
Mercury - chemistry
Mutation
Oxidants - chemistry
Oxidation-Reduction
Peroxides - chemistry
Potassium Channels - chemistry
Potassium Channels - genetics
Potassium Channels, Voltage-Gated
Rats
Sequence Deletion
Xenopus laevis
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Summary:Slowly activating IsK channels were expressed in Xenopus oocytes and exposed to oxidative agents. Oxidative treatment reduced the resulting current IsK, while no inhibition was observed for IsK protein mutants carrying a Ser mutation instead of a highly conserved Cys residue in the intracellular domain. In contrast, Hg2+, which may not only oxidize thiol groups but also form chelates with dibasic amino acids, caused a use-dependent, positive regulation of IsK. This effect was reversed in an IsK protein mutant with a deletion in the extracellular domain. These data suggest opposite effects of peroxides and Hg2+ on IsK, a peroxide-mediated IsK inhibition by intracellular oxidation and a Hg(2+)-mediated IsK increase, caused by extracellular Hg2+ chelation of the IsK protein.
ISSN:0021-9258