Ion permeability induced in artificial membranes by the ATP/ADP antiporter.
The hypothesis on the additional function of the ATP/ADP antiporter (ANT) as uncoupling protein has been tested in proteoliposomes and planar bilayer phospholipid membranes (BLM). It is found that dissipation of the light-induced delta pH in the dark is very much faster in ANT-bacteriorhodopsin proteoliposomes than in proteoliposomes containing bacteriorhodopsin as the only protein. Mersalyl treatment of ANT-bacteriorhodopsin proteoliposomes causes further increase in the delta pH dissipation rate due to formation of a high conductance pore. The properties of this pore are studied on ANT incorporated to BLM. They proved to be similar to those of so-called multiple conductance channel or permeability transition pore of inner mitochondrial membrane. The conductance of the single channel is as high as 2.2 nS. The channel fails to discriminate between K+, Na+, H+ and Cl-. Thus the obtained data are consistent with the assumption that native and modified ANT might function as an H(+)-specific conductor and as a permeability transition pore, respectively.
Tikhonova
I M
IM
A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russian Federation.
Andreyev AYu
Antonenko YuN
Kaulen
A D
AD
Komrakov AYu
Skulachev
V P
VP
D000408:Alamethicin / Q000494:pharmacology; D000838:Anions; D001436:Bacteriorhodopsins / Q000378:metabolism; D002412:Cations; D002463:Cell Membrane Permeability / Q000187:drug effects*; D004553:Electric Conductivity; D006096:Gramicidin / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008027:Light; D008051:Lipid Bilayers / Q000378:metabolism; D008081:Liposomes / Q000378:metabolism*; D008634:Mersalyl / Q000494:pharmacology; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism*
D000838:Anions; D002412:Cations; D008051:Lipid Bilayers; D008081:Liposomes; D006096:Gramicidin; D000408:Alamethicin; D001436:Bacteriorhodopsins; D008634:Mersalyl; D000226:Mitochondrial ADP, ATP Translocases