Diwan J J, Haley T, Sanadi D R
Biology Department, Rensselaer Polytechnic Institute, Troy, New York 12180-3590.
Biochem Biophys Res Commun. 1988 May 31;153(1):224-30. doi: 10.1016/s0006-291x(88)81212-9.
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.
