Reconstitution of transmembrane K+ transport with a 53 kilodalton mitochondrial protein.
A 53 kDa protein has been purified from a Triton X-100 extract of liver mitochondrial membranes, by affinity chromatography on immobilized quinine, a K+ transport inhibitor. KCl-containing lipid vesicles reconstituted with this protein lose K+ to a medium low in K+ faster than vesicles lacking protein. With bacteriorhodopsin reconstituted in vesicles containing K+, light induces faster development of a pH gradient if the 53 kDa protein is included during vesicle preparation. This effect is like that of valinomycin, which catalyzes K+ efflux, dissipating the membrane potential arising from H+ entry. Evidence that vesicles containing the 53 kDa protein are permeable to K+, but exhibit low permeability to H+, indicates that this protein acts as a K+ uniporter.
Diwan
J J
JJ
Biology Department, Rensselaer Polytechnic Institute, Troy, New York 12180-3590.
Haley
T
T
Sanadi
D R
DR
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D004591:Electrophoresis, Polyacrylamide Gel; D008297:Male; D008930:Mitochondria, Liver / Q000032:analysis*; D008970:Molecular Weight; D011188:Potassium / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats
D011506:Proteins; D011188:Potassium