PROTEIN PHOSPHORYLATION IN VITRO IN BRAIN TUBULIN PREPARATIONS: EFFECTS OF Zn2+ AND CYCLIC NUCLEOTIDES
- 1 July 1977
- journal article
- research article
- Published by Wiley in Journal of Neurochemistry
- Vol. 29 (1) , 115-120
- https://doi.org/10.1111/j.1471-4159.1977.tb03932.x
Abstract
Abstract— Endogenous protein phosphorylation has been studied during in vitro polymerization of microtubules by incubating a purified tubulin preparation at 37°C in the presence of radioactive ATP. At optimal conditions the rate of phosphorylation was found to follow the course of polymerization by a shift to a lower rate at the polymerization plateau.Zn2+ at 0.5 mm was shown to stimulate phosphorylation, mainly of tubulin‐associated proteins (mol wt 110,000 and 175,000,) and to a lesser extent of tubulin. The effect occurred at Zn2+‐concentrations which induce formation of tubulin sheet polymers, which suggests that the state of aggregation of tubulin is of importance for the phosphorylation. In contrast to Zn2+, Mg2+ only increased phosphorylation of the high molecular weight proteins, and to a lesser degree. The stimulation by Zn2+ or Mg2+ was potentiated by cyclic AMP or cyclic GMP.A low concentration of Zn2+ (5 μm) or cyclic GMP at 10 μm inhibited phosphorylation, possibly by interaction with a co‐existing protein phosphatase.This publication has 29 references indexed in Scilit:
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