2,3-Butanedione monoxime (BDM) inhibition of delayed rectifier DRK1 (Kv2.1) potassium channels expressed in Xenopus oocytes.
DRK1 is a cloned K+ channel from rat brain with consensus sites for protein kinase-dependent phosphorylation that might be expected to be functionally regulated by phosphorylation. 2,3-Butane-dione-monoxime (BDM) chemically removes phosphate groups from many proteins, and its action on DRK1 channels was examined after expression of DRK1 cRNA in Xenopus oocytes. In two-microelectrode voltage-clamp experiments, the application of BDM to the bath inhibited DRK1 current (ki = 16.6 mM, H = 0.96) rapidly and reversibly, with a time course similar to the time course of solution change within the bath. DRK1 current was inhibited at all potentials; the time course of current activation, deactivation and inactivation were unaffected by BDM. In inside-out patch-clamp experiments, the application of BDM to the cytoplasmic surface similarly inhibited channel activity rapidly and reversibly (ki = 10.7 mM, H = 1.01) in the absence of rephosphorylating substrates. These results are inconsistent with a phosphatase effect, because such an effect should be irreversible in cell-free, ATP-free patches. Instead, the results suggest that BDM can inhibit DRK1 channels directly from inside or outside of the membrane.
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Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri.
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D000818:Animals; D001692:Biological Transport; D003001:Cloning, Molecular; D003931:Diacetyl / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004058:Diffusion; D008564:Membrane Potentials / Q000187:drug effects; D009865:Oocytes; D015221:Potassium Channels / Q000187:drug effects* / Q000235:genetics; D051381:Rats; D014981:Xenopus
D015221:Potassium Channels; C004717:diacetylmonoxime; D003931:Diacetyl