The Journal of General Physiology, Vol 41, 585-594,
Copyright © 1958 by The Rockefeller University Press
THE ACTIVE TRANSPORT OF Mg++ AND Mn++ INTO THE YEAST CELL
A. Rothstein 1,
A. Hayes 1,
D. Jennings 1, and
D. Hooper 1
1 From the Division of Pharmacology, Department of Radiation Biology, The University of Rochester School of Medicine and Dentistry, Rochester, New York
Certain bivalent cations, particularly Mg++ and Mn++, can be absorbed by yeast cells, provided that glucose is available, and that phosphate is also absorbed. The cation absorption is stimulated by potassium in low concentrations, but inhibited by higher concentrations. From the time course studies, it is apparent that the absorption rather than the presence of phosphate and the potassium is the important factor. Competition studies with pairs of cations indicate that binding on the surface of the cell is not a prerequisite to absorption. The absorption mechanism if highly selective for Mg++ and Mn++, as compared to Ca++, Sr++, and UO2++, whereas the binding affinity is greatest for UO2++, with little discrimination between Mg++, Ca++, Mn++, and Sr++. In contrast to the surface-bound cations which are completely exchangeable, the absorbed cations are not exchangeable. It is concluded that Mg++ and Mn++ are actively transported into the cell by a mechanism involving a phosphate and a protein constituent.
Submitted on July 17, 1957
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