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.
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