Specific association of phosphatidylinositol 3-kinase with the protooncogene product Cbl in Fc gamma receptor signaling.

A tyrosine-phosphorylated protein with a molecular mass of 115 kDa was reported to be tightly associated with the p85 regulatory subunit of phosphatidylinositol (PI) 3-kinase, when the enzyme was essentially activated upon ligand engagement of Fc gamma receptors (Fc gamma R) leading to engulfment of IgG-coated erythrocytes by phagocytes [Ninomiya ...
et al. (1994) J. Biol. Chem. 269, 22732-22737]. Here, the 115-kDa protein is identified as the product of human c-cbl protooncogene. Cross-linking of Fc gamma RII on the surface of THP-1 cells triggered (a) prominent tyrosine phosphorylation of Cbl, (b) activation of PI 3-kinase that was immunoprecipitated with the anti-Cbl or the anti-phosphotyrosine antibody, and (c) specific association of Cbl with p85. Thus, Cbl functions in phagocytes as a result of its association with PI 3-kinase in response to Fc gamma R ligation.
Mesh Terms:
Antibodies, Monoclonal, Cell Line, Cross-Linking Reagents, Enzyme Activation, Humans, Monocytes, Phosphatidylinositol 3-Kinases, Phosphorylation, Phosphotransferases (Alcohol Group Acceptor), Phosphotyrosine, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-cbl, Receptors, IgG, Signal Transduction, Ubiquitin-Protein Ligases
FEBS Lett.
Date: Mar. 11, 1996
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