Multiple Grb2-protein complexes in human cancer cells.
Grb2 is an SH2/SH3 domain-containing adaptor protein that links receptor tyrosine kinases to the ras signaling pathway. The Grb2-SH2 domain binds phosphotyrosine sequences on activated tyrosine kinases, and one target of the SH3 domains is the ras-nucleotide-exchange factor Sos1. We have examined Grb2-protein interactions in human cancer cells that over-express the receptor tyrosine kinase erbB2. Our results show that the 2 Grb2-SH3 domains complex with Sos1, dynamin and at least 4 other proteins (p228, p140, p55, p28) in these cells. The 2 Grb2-SH3 domains bind these proteins differently, with the N-terminal SH3 domain interacting preferentially with p228, Sos1, p140 and dynamin. The C-terminal SH3 domain has higher affinity toward p28. The Grb2-SH3 domain interactions appear to be similar in erbB2 over-expressing breast, ovarian and lung cancer cells. Also, the major tyrosine-phosphorylated proteins that associate with Grb2 in erbB2 over-expressing cancer cells appear to be erbB2 and Shc. The multiple Grb2-SH3 domain interactions in these cells may mediate novel cellular functions.
Sastry
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Department of Biochemistry, Lombardi Cancer Center, Georgetown University Medical Center, Washington, DC 20007. USA.
Cao
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King
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D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D051380:GRB2 Adaptor Protein; D011905:Genes, ras; D006801:Humans; D046911:Macromolecular Substances; D051379:Mice; D009363:Neoplasm Proteins / Q000032:analysis* / Q000378:metabolism; D009369:Neoplasms / Q000737:chemistry* / Q000473:pathology; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; D046911:Macromolecular Substances; D009363:Neoplasm Proteins; D019000:Phosphotyrosine; D011506:Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; C495948:GRB2 protein, human; C495949:Grb2 protein, mouse