Tyrosines1234-1235 are critical for activation of the tyrosine kinase encoded by the MET proto-oncogene (HGF receptor)

Paola Longati, Alberto Bardelli, Carola Ponzetto, Luigi Naldini, Paolo M. Comoglio

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Abstract

The tyrosine kinase encoded by the MET proto-oncogene (p190MET) is the receptor for Hepatocyte Growth Factor/ Scatter Factor (HGF/SF). Previous work has shown that autophosphorylation of p190MET enhances its enzymatic activity and that the major phosphorylation site is Tyr1235, located in the catalytic domain. This residue is part of a 'three tyrosine' motif, including Tyr1230, Tyr1234, and Tyr1235, conserved in several other receptor kinases. We studied the role of these tyrosines in the positive regulation of the p190MET kinase by site-directed mutagenesis. Substitution of either Tyr1235 or Tyr1234 with phenylalanine severely reduced the in vitro kinase activity toward exogenous substrates. Kinetic experiments showed that the residual activity of these mutants could still be enhanced by autophosphorylation. Phosphopeptide mapping indicated that, in the absence of Tyr1235, Tyr1234 is phosphorylated. Only the replacement of both Tyr1234 and Tyr1235 yielded a mutant which completely lost the ability to be activated by autophosphorylation. In stable transfectants expressing the HGF/SF receptor with single substitution of either Tyr1234 or Tyr1235 the response to HGF/SF was impaired. The ligand did not induce tyrosine phosphorylation of the receptor nor stimulated chemotaxis. These data show that Tyr1234 and Tyr1235 are critical for the activation of the HGF/SF receptor kinase both in vitro and in response to the ligand in intact cells.

Original languageEnglish
Pages (from-to)48-57
Number of pages10
JournalOncogene
Volume9
Issue number1
Publication statusPublished - Jan 1994

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Proto-Oncogene Proteins c-met
Hepatocyte Growth Factor
Proto-Oncogenes
Protein-Tyrosine Kinases
Phosphotransferases
Tyrosine
Phosphorylation
Ligands
Phosphopeptides
Aptitude
Chemotaxis
Site-Directed Mutagenesis
Phenylalanine
Catalytic Domain

ASJC Scopus subject areas

  • Cancer Research
  • Genetics
  • Molecular Biology

Cite this

Tyrosines1234-1235 are critical for activation of the tyrosine kinase encoded by the MET proto-oncogene (HGF receptor). / Longati, Paola; Bardelli, Alberto; Ponzetto, Carola; Naldini, Luigi; Comoglio, Paolo M.

In: Oncogene, Vol. 9, No. 1, 01.1994, p. 48-57.

Research output: Contribution to journalArticle

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AU - Bardelli, Alberto

AU - Ponzetto, Carola

AU - Naldini, Luigi

AU - Comoglio, Paolo M.

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