A novel potassium channel in lymphocyte mitochondria.
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.
Szabò
Ildikò
I
Department of Biology, University of Padova, 35121 Padova, Italy. ildi@civ.bio.unipd.it
Bock
Jurgen
J
Jekle
Andreas
A
Soddemann
Matthias
M
Adams
Constantin
C
Lang
Florian
F
Zoratti
Mario
M
Gulbins
Erich
E
D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D019169:Jurkat Cells; D051664:Kv1.3 Potassium Channel; D008214:Lymphocytes / Q000378:metabolism*; D008564:Membrane Potentials; D008854:Microscopy, Electron; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism*; D009498:Neurotoxins / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000737:chemistry*; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism*; D012604:Scorpion Venoms; D013601:T-Lymphocytes / Q000276:immunology; D014162:Transfection
C496973:KCNA3 protein, human; D051664:Kv1.3 Potassium Channel; D009498:Neurotoxins; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012604:Scorpion Venoms; C077910:margatoxin