Stimulation of phosphatase release from cultured tobacco cells by divalent cations

概要

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Upon addition of divalent cations to the incubation medium of cultured tobacco cells, the release of phosphatase into the medium increased and the time course of the release became biphasic. A rapid release (phase I release) occurred instantaneously after the addition and then a release at a constant rate (phase II release) followed. Sodium and potassium ions did not affect the enzyme release. Lanthanum ions caused the biphasic enzyme release but inhibited the phase II release. The effects of temperature and metabolic inhibitors indicated that phase I release was limited by a diffusion process but phase II release was limited by an enzymatic reaction requiring metabolic energy. From the results it was concluded that divalent cations enhanced the enzyme release not only by stimulating the transport of enzyme to the outside of the cell membrane, but also by liberating the enzyme retained on the exterior of the cells, e.g., the cell walls. The released phosphatase could be separated into two fractions, F-I and F-II. Only F-I was released by phase I release, while both F-I and F-II resulted from phase II release. This indicated that F-I was preferentially trapped on the exterior of the cells.
日本植物生理学会の論文