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Effects of Zn 2+ ions on protein phosphorylation in epithelial cell membranes
Author(s) -
Alitalo Kari,
KeskiOja Jorma,
Bornstein Paul
Publication year - 1983
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041150314
Subject(s) - phosphorylation , divalent , phosphoprotein , threonine , membrane , phosphatase , vesicle , chemistry , serine , protein phosphorylation , dephosphorylation , kinase , biochemistry , biophysics , protein kinase a , biology , organic chemistry
The regulation of protein phosphorylation by Zn 2+ ions and by other divalent cations was studied in membrane vesicles from a normal mouse epithelial cell line, MMC‐E ( Mus musculus castaneous ). Four major phosphoacceptor polypeptides were found in these membranes. Micromolar concentrations of Zn 2+ ions inhibited the phosphorylation of the epidermal growth factor (EGF) receptor and of threonine residues in a 47,000‐dalton polypeptide. In contrast, two polypeptides with molecular weights of 54,000 and 57,000 showed increased phosphorylation, mainly of serine residues, in the p. esence of Zn 2+ ions. These results were not obtained using similar concentrations of other divalent cations and were apparently not due to an effect of Zn 2+ ions on phosphoprotein phosphatases. Thus, the effects of Zn 2+ ions on protein phosphorylation in membrane vesicles are complex and are not restricted to an inhibition of a single protein phosphatase or kinase.