The two major sites of cbl tyrosine phosphorylation in abl-transformed cells select the crkL SH2 domain.
We recently found that the 120-kD protein product of the c-cbl oncogene is tyrosine phosphorylated in tumor cells generated by bcr-abl or v-abl and that p120cbl will associate with these proteins in vivo. We also found an oncogenic form of cbl protein in the 70Z/3 pre-B cell lymphoma which exhibits deregulated tyrosine phosphorylation. These findings have led us to broaden our study of cbl's involvement in abl-mediated tumorigenesis. Here we show by immunodepletion that cbl is the major 120-kD tyrosine phosphorylated protein in cells which express activated forms of the abl oncogene. We also demonstrate that tyrosine phosphorylation of pl20cbl in bcr-abl transformed cells does not alter its subcellular localization. In addition we show that the oncogenic 7OZ/3 form of cbl exhibits enhanced tyrosine phosphorylation in v-abl infected cells and that cbl is heavily tyrosine phosphorylated in hemopoietic cells transformed by v-src. Finally this study identifies two sites that are essential for the tyrosine phosphorylation of cbl in abl-transformed cells. These sites conform to the preferred abl kinase substrate sequence of YXXP and we show that following phosphorylation they mediate an association with the crkL SH2 domain.
Andoniou
C E
CE
Department of Pathology, The University of Western Australia, Nedlands, Australia.
Thien
C B
CB
Langdon
W Y
WY
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000378:metabolism; D002461:Cell Line, Transformed; D003600:Cytosol / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D016313:Genes, abl; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D051381:Rats; D014443:Tyrosine / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D016044:Fusion Proteins, bcr-abl; C493849:Cbl protein, mouse