A family of calcium-dependent potassium channels from rat brain

Neuron. 1989 Jan;2(1):1031-41. doi: 10.1016/0896-6273(89)90227-4.

Abstract

By incorporating rat brain plasma membrane vesicles into planar lipid bilayers, we have found and characterized four types of Ca2(+)-activated K+ channels. The unitary conductances of these channels are 242 +/- 14 pS, 236 +/- 16 pS, 135 +/- 10 pS, and 76 +/- 6 pS in symmetrical 150 mM KCI buffers. These channels share a number of properties. They are all activated by depolarizing voltages, activated by micromolar concentrations of internal Ca2+ with a Hill coefficient for Ca2+ activation of between 2 and 3, noninactivating under our assay conditions, blocked by low millimolar concentrations of TEA from the outside, apamin-insensitive, and very selective for K+ over Na+ and Cl-. Three of the four channels are also blocked by nanomolar concentrations of charybdotoxin. One of the high conductance Ca2(+)-activated K+ channels is novel in that it is not blocked by charybdotoxin and exhibits gating kinetics highlighted by long closed times and long open times. This family of closely related Ca2(+)-activated K+ channels may share structural domains underlying particular functions.

Publication types

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

MeSH terms

  • Animals
  • Brain / physiology*
  • Calcium / pharmacology*
  • Cell Membrane / physiology
  • Electric Conductivity
  • Kinetics
  • Lipid Bilayers
  • Membrane Fusion
  • Potassium Channels / drug effects
  • Potassium Channels / physiology*
  • Rats

Substances

  • Lipid Bilayers
  • Potassium Channels
  • Calcium