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Energy Coupling to Periplasmic Binding Protein-Dependent Transport Systems: Stoichiometry of ATP Hydrolysis during Transport in vivo
M. L. Mimmack, M. P. Gallagher, S. R. Pearce, S. C. Hyde, I. R. Booth and C. F. Higgins
Proceedings of the National Academy of Sciences of the United States of America
Vol. 86, No. 21 (Nov. 1, 1989), pp. 8257-8261
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/34848
Page Count: 5
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Periplasmic binding protein-dependent transport systems mediate the accumulation of many diverse substrates in prokaryotic cells. Similar transport systems, including the P-glycoprotein responsible for multidrug resistance in human tumors, are also found in eukaryotes. The mechanism by which energy is coupled to the accumulation of substrate by these transport systems has been controversial. In this paper we demonstrate that ATP hydrolysis occurs in vivo concomitantly with transport. These data strongly suggest that ATP hydrolysis directly energizes substrate accumulation by these transport systems. The apparent stoichiometry is one to two molecules of ATP hydrolyzed per molecule of substrate transported.
Proceedings of the National Academy of Sciences of the United States of America © 1989 National Academy of Sciences