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PHOSPHOPROTEIN PHOSPHATASE OF PINEAL GLAND: SOME PROPERTIES OF THE ENZYME AND THE IDENTIFICATION OF AN ENDOGENOUS ACTIVATOR
Author(s) -
Yang H.Y. T.,
Costa E.,
Majane E. A.,
Hong J.
Publication year - 1977
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1977.tb10671.x
Subject(s) - enzyme , biochemistry , phosphoprotein , activator (genetics) , dephosphorylation , phosphatase , cytosol , trypsin , endogeny , chemistry , alkaline phosphatase , cell fractionation , enzyme activator , enzyme assay , phosphorylation , biology , microbiology and biotechnology , receptor
Abstract— Both soluble and insoluble fractions of rat pineal glands catalyze the dephosphorylation of phosphohistone. The phosphoprotein phosphatase in cytosol as well as in insoluble fraction is inhibited by ZnCl 2 and NaF. Guanosine triphosphate, ATP and MnCl 2 activate the soluble enzyme but not the enzyme in the insoluble fraction suggesting that with solubilization from membranes some unfunctional changes of the enzyme may occur. Fractionation of the soluble enzyme preparation revealed the existence of two forms of enzyme differing in molecular weight. These two forms can be further differentiated by their sensitivities to MnCl 2 and deoxycholate. A thermostable factor which activates the soluble but not the insoluble enzyme was demonstrated in both beef and rat pineal glands. The thermostable factor is protein in nature because it is nondialyzable and trypsin labile. Whether in vivo the endogenous activator mediates the regulation of the phosphoprotein phosphatase in pineal remains to be investigated.