THE DISTRIBUTION OF PERMEANT IONS DEMONSTRATES THE PRESENCE OF AT LEAST 2 DISTINCT ELECTRICAL GRADIENTS IN BLOOD-STREAM FORMS OF TRYPANOSOMA-BRUCEI

被引:24
作者
NOLAN, DP [1 ]
VOORHEIS, HP [1 ]
机构
[1] UNIV DUBLIN TRINITY COLL,DEPT BIOCHEM,DUBLIN 2,IRELAND
来源
EUROPEAN JOURNAL OF BIOCHEMISTRY | 1991年 / 202卷 / 02期
关键词
D O I
10.1111/j.1432-1033.1991.tb16390.x
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The distribution of Rb-86+ and the radiolabelled lipophilic cation [H-3]methyltriphenylphosphonium (MePh3P+) was used to investigate the membrane potentials that exist in bloodstream forms of Trypanosoma brucei. Even after correction for binding to cellular constituents, the accumulation of MePh3P+ was approximately tenfold greater than the accumulation of Rb+ under resting conditions. The addition of low concentrations of carbonylcyanide p-trifluoromethoxyphenylhydrazone or valinomycin reduced the accumulation of MePh3P+ tenfold without perturbing the accumulation of Rb+. Although selective permeabilization of the plasma membrane abolished the accumulation of Rb+ and caused a substantial decrease in the accumulation of MePh3P+, a significant carbonylcyanide-p-trifluoromethoxyphenylhydrazone-sensitive accumulation of MePh3P+ persisted under these conditions. These data were consistent with the presence of at least two distinct membrane potentials (DELTA-PSI) in bloodstream forms of T. brucei; a potential across the plasma membrane (DELTA-PSI(p)) and an additional DELTA-PSI, generated by the electrogenic movement of H+, across the membrane of an intracellular organelle that possesses no electrical permeability to Rb+ or K+.
引用
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页码:411 / 420
页数:10
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