A novel potassium channel in lymphocyte mitochondria

J Biol Chem. 2005 Apr 1;280(13):12790-8. doi: 10.1074/jbc.M413548200. Epub 2005 Jan 4.

Abstract

The margatoxin-sensitive Kv1.3 is the major potassium channel in the plasma membrane of T lymphocytes. Electron microscopy, patch clamp, and immunological studies identified the potassium channel Kv1.3, thought to be localized exclusively in the cell membrane, in the inner mitochondrial membrane of T lymphocytes. Patch clamp of mitoplasts and mitochondrial membrane potential measurements disclose the functional expression of a mitochondrial margatoxin-sensitive potassium channel. To identify unambiguously the mitochondrial localization of Kv1.3, we employed a genetic model and stably transfected CTLL-2 cells, which are genetically deficient for this channel, with Kv1.3. Mitochondria isolated from Kv1.3-reconstituted CTLL-2 expressed the channel protein and displayed an activity, which was identical to that observed in Jurkat mitochondria, whereas mitochondria of mock-transfected cells lacked a channel with the characteristics of Kv1.3. Our data provide the first molecular identification of a mitochondrial potassium conductance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Western
  • Cell Line
  • Cell Membrane / metabolism
  • Flow Cytometry
  • Humans
  • Intracellular Membranes / metabolism
  • Jurkat Cells
  • Kv1.3 Potassium Channel
  • Lymphocytes / metabolism*
  • Membrane Potentials
  • Microscopy, Electron
  • Microscopy, Electron, Transmission
  • Mitochondria / metabolism*
  • Neurotoxins / pharmacology
  • Patch-Clamp Techniques
  • Potassium Channels / chemistry*
  • Potassium Channels, Voltage-Gated / metabolism*
  • Scorpion Venoms
  • T-Lymphocytes / immunology
  • Transfection

Substances

  • KCNA3 protein, human
  • Kv1.3 Potassium Channel
  • Neurotoxins
  • Potassium Channels
  • Potassium Channels, Voltage-Gated
  • Scorpion Venoms
  • margatoxin