Phosphorylation of serine 985 negatively regulates the hepatocyte growth factor receptor kinase

Lucia Gandino, Paola Longati, Enzo Medico, Maria Prat, Paolo M. Comoglio

Research output: Contribution to journalArticlepeer-review


The receptor for hepatocyte growth factor/scatter factor (HGF/SF) is an αβ tyrosine kinase of 190 kDa which mediates growth and motility in several cell types. We have previously shown that tyrosine autophosphorylation enhances the receptor kinase activity, while serine phosphorylation by protein kinase C or other Ca2+-dependent kinase(s) is inhibitory. We now identify Ser985 as the major phosphorylation site for the protein kinases responsible for such inhibition. Both phorbol esters or Ca2+ ionophore treatment induces phosphorylation of the same tryptic phosphopeptide corresponding to the sequence Leu983-Arg987 located in the juxtamembrane domain of the receptor β chain. Purified protein kinase C phosphorylates in vitro a synthetic peptide (V14S) including Ser985. Trypsin digestion of the phosphorylated V14S generates a single phosphopeptide comigrating in reverse-phase high performance liquid chromatography with the tryptic peptide phosphorylated in vivo. Phorbol ester treatment of cultured cells inhibits the ligand-induced tyrosine autophosphorylation of the receptor. In vitro, Ser985 phosphorylation inhibits the receptor tyrosine kinase activity on exogenous substrates. Substitution of Ser985 by site-directed mutagenesis results in increased tyrosine phosphorylation of the receptor and abolishes down-modulation by protein kinase C. These data show that phosphorylation of Ser985 is a key mechanism for the negative regulation of HGF/SF receptor.

Original languageEnglish
Pages (from-to)1815-1820
Number of pages6
JournalJournal of Biological Chemistry
Issue number3
Publication statusPublished - Jan 21 1994

ASJC Scopus subject areas

  • Biochemistry


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