ATP inhibition of a mouse brain large-conductance K+ (mslo) channel variant by a mechanism independent of protein phosphorylation

Authors


  • Author's present address

    A. G. Clark: Organon Laboratories Ltd, Newhouse, Lanarkshire ML1 5SH, UK.

Corresponding author M. J. Shipston: Membrane Biology Group, Department of Biomedical Sciences, University of Edinburgh, Medical School, Teviot Place, Edinburgh EH8 9AG, UK. Email: mike.shipston@ed.ac.uk

Abstract

  • 1We investigated the effect of ATP in the regulation of two closely related cloned mouse brain large conductance calcium- and voltage-activated potassium (BK) channel α-subunit variants, expressed in human embryonic kidney (HEK 293) cells, using the excised inside-out configuration of the patch-clamp technique.
  • 2The mB2 BK channel α-subunit variant expressed alone was potently inhibited by application of ATP to the intracellular surface of the patch with an IC50 of 30 μM. The effect of ATP was largely independent of protein phosphorylation events as the effect of ATP was mimicked by the non-hydrolysable analogue 5′-adenylylimidodiphosphate (AMP-PNP) and the inhibitory effect of ATPγS was reversible.
  • 3In contrast, under identical conditions, direct nucleotide inhibition was not observed in the closely related mouse brain BK channel α-subunit variant mbr5. Furthermore, direct nucleotide regulation was not observed when mB2 was functionally coupled to regulatory β-subunits.
  • 4These data suggest that the mB2 α-subunit splice variant could provide a dynamic link between cellular metabolism and cell excitability.

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