Staurosporine inhibits a tyrosine protein kinase in human hepatoma cell membranes

Robert J. Fallon

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58 Scopus citations


Membranes from the human hepatoma cell line HepG2 mediate the phosphorylation on tyrosine of the asialoglycoprotein receptor. Manganese was the preferred divalent for phosphorylation although magnesium was effective at an 8-fold higher concentration. Calcium was ineffective at promoting phosphorylation and zinc was inhibitory. The protein kinase inhibitor staurosporine blocked asialoglycoprotein receptor phosphorylation on tyrosine in nanomolar concentrations (IC50= 70 nM). In contrast another protein kinase C inhibitor, H7, was not inhibitory, suggesting that the effect of staurosporine was not mediated by protein kinase C inhibition. Concentrations of staurosporine that inhibit receptor phosphorylation by greater than 90% did not inhibit the phosphorylation of other protein substrates identified on SDS-polyacrylamide gels. These data suggest that staurosporine selectively and directly inhibits a membrane-associated tyrosine protein kinase.

Original languageEnglish (US)
Pages (from-to)1191-1196
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number3
StatePublished - Aug 16 1990

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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