Activation of phosphatidylinositol-3 kinase by nerve growth factor involves indirect coupling of the trk proto-oncogene with src homology 2 domains.
Neuron
; 9(4): 769-77, 1992 Oct.
Article
em En
| MEDLINE
| ID: mdl-1382475
ABSTRACT
Growth factor receptor tyrosine kinases can form stable associations with intracellular proteins that contain src homology (SH) 2 domains, including the p85 regulatory subunit of phosphatidylinositol (PI)-3 kinase. The activation of this enzyme by growth factors is evaluated in PC12 pheochromocytoma cells and NIH 3T3 fibroblasts expressing the pp140c-trk nerve growth factor (NGF) receptor (3T3-c-trk). NGF causes the rapid stimulation of PI-3 kinase activity detected in anti-phosphotyrosine, but not in anti-trk, immunoprecipitates. This effect coincides with the tyrosine phosphorylation of two proteins, with molecular masses of of 100 kd and 110 kd, that coimmunoprecipitate with p85. Similar phosphorylation patterns are induced when an immobilized fusion protein containing the amino-terminal SH2 domain of p85 is used to precipitate tyrosine-phosphorylated proteins. Thus, although NGF produces the rapid activation of PI-3 kinase through a mechanism that involves tyrosine phosphorylation, there is no evidence for tyrosine phosphorylation of p85, or for its ligand-dependent association with the NGF receptor. Perhaps another phosphoprotein may link the NGF receptor to this enzyme.
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Fosfotransferases
/
Proteínas Tirosina Quinases
/
Proto-Oncogenes
/
Genes src
/
Proteínas Proto-Oncogênicas
/
Fatores de Crescimento Neural
Idioma:
En
Ano de publicação:
1992
Tipo de documento:
Article