Intermediate conductance Ca2+-activated potassium channel (KCa3.1) in the inner mitochondrial membrane of human colon cancer cells.
Patch-clamping mitoplasts isolated from human colon carcinoma 116 cells has allowed the identification and characterization of the intermediate conductance Ca(2+)-activated K(+)-selective channel K(Ca)3.1, previously studied only in the plasma membrane of various cell types. Its identity has been established by its biophysical and pharmacological properties. Its localisation in the inner membrane of mitochondria is indicated by Western blots of subcellular fractions, by recording of its activity in mitochondria made fluorescent by a mitochondria-targeted fluorescent protein and by the co-presence of channels considered to be markers of the inner membrane. Moderate increases of mitochondrial matrix [Ca(2+)] will cause mtK(Ca)3.1 opening, thus linking inner membrane K(+) permeability and transmembrane potential to Ca(2+) signalling.
De Marchi
Umberto
U
Department of Biomedical Sciences, University of Padova, Padova, Italy.
Sassi
Nicola
N
Fioretti
Bernard
B
Catacuzzeno
Luigi
L
Cereghetti
Grazia M
GM
Szabò
Ildikò
I
Zoratti
Mario
M
D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D045744:Cell Line, Tumor / Q000166:cytology / Q000378:metabolism; D003110:Colonic Neoplasms / Q000378:metabolism*; D006801:Humans; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure; D051336:Mitochondrial Membranes / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism
D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C496923:KCNN4 protein, human; D011188:Potassium; D002118:Calcium