A membrane-bound human placental protein kinase activated by endogenous polypeptides

Mossaad Abdel-Ghany, Shun Nakamura, Javier Navarro, Efraim Racker

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Abstract

A protein kinase (PPdPK) was purified from plasma membranes of human placenta. Phosphorylation of casein, but not of phosvitin or lactalbumin, by [γ-32P]ATP in the presence of PPdPK was stimulated about 10-fold by naturally occurring polypeptides prepared from avariety of sources similar to the procedure of Roberts et al. (Proc. Natl. Acad. Sci. U.S.A. 77, 3494-3498, 1980). The amino acid phos-phorylated on casein was serine. According to gel exclusion chromatography the mol.wt, of PPdPK was 95 000. In autoradiograms, following polyacrylamide-gel electrophoresis, the autophosphorylation of PPdPK was greatly enhanced by the polypeptide activators.

Original languageEnglish (US)
Pages (from-to)275-282
Number of pages8
JournalBioscience Reports
Volume3
Issue number3
DOIs
StatePublished - Mar 1983
Externally publishedYes

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ASJC Scopus subject areas

  • Cell Biology
  • Biochemistry, Genetics and Molecular Biology(all)

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