A calcium switch for the functional coupling between alpha (hslo) and beta subunits (KV,Ca beta) of maxi K channels

FEBS Lett. 1996 Mar 11;382(1-2):84-8. doi: 10.1016/0014-5793(96)00151-2.

Abstract

KV,Ca beta subunit dramatically increases the apparent calcium sensitivity of the alpha subunit of MaxiK channels when probed in the micromolar [Ca2+]i range. Analysis in a wide range of [Ca2+]i revealed that this functional coupling is exquisitely modulated by [Ca2+]i. Ca2+ ions switch MaxiK alpha+beta complex into a functionally coupled state at concentrations beyond resting [Ca2+]i. At [Ca2+] < or = 100 nM, MaxiK activity becomes independent of Ca2+, is purely voltage-activated, and its functional coupling with its beta subunit is released. The functional switch develops at [Ca2+]i that occur during cellular excitation, providing the molecular basis of how MaxiK channels regulate smooth muscle excitability and neurotransmitter release.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Calcium / pharmacology
  • Calcium / physiology*
  • Cations, Divalent
  • Cattle
  • Female
  • Humans
  • Ion Channel Gating / drug effects
  • Ion Channel Gating / physiology*
  • Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
  • Large-Conductance Calcium-Activated Potassium Channel beta Subunits
  • Large-Conductance Calcium-Activated Potassium Channels
  • Molecular Sequence Data
  • Myometrium
  • Oocytes
  • Potassium Channels / genetics
  • Potassium Channels / physiology*
  • Potassium Channels, Calcium-Activated*
  • Sequence Homology, Amino Acid
  • Xenopus laevis

Substances

  • Cations, Divalent
  • KCNMA1 protein, human
  • Large-Conductance Calcium-Activated Potassium Channel alpha Subunits
  • Large-Conductance Calcium-Activated Potassium Channel beta Subunits
  • Large-Conductance Calcium-Activated Potassium Channels
  • Potassium Channels
  • Potassium Channels, Calcium-Activated
  • Calcium

Associated data

  • GENBANK/U25138