The high transforming potency of erbB-2 and ret is associated with phosphorylation of paxillin and a 23 kDa protein.
Two-dimensional gel maps of proteins phosphorylated by the epidermal growth factor receptor (EGFR) and erbB-2 kinases were obtained, to investigate the molecular basis of the different biological properties of these two molecules. Several proteins were phosphorylated by EGFR or erbB-2 with different stoichiometry. Differences were either quantitative or qualitative. In NIH3T3 cells, erbB-2 is 100-fold more transforming than EGFR. In the same cell line several proteins were preferentially phosphorylated by erbB-2, as compared to EGFR. To identify which of these substrates might be directly involved in mitogenic signaling, we obtained two-dimensional maps of proteins phosphorylated on tyrosine by EGFR/ret and an EGFR/erbB-2TK chimeric receptors. Both these chimerae behaved indistinguishably from erbB-2 in a number of bioassays and potently transformed NIH3T3 cells. Paxillin and a 23 kDa substrate were invariably phosphorylated to higher stoichiometry whenever potent mitogenic and transforming signals were activated. We propose that paxillin and the 23 kDa substrate are important elements in the erbB-2 and ret-activated mitogenic and transforming signaling.
Romano
A
A
Laboratory of Experimental Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Wong
W T
WT
Santoro
M
M
Wirth
P J
PJ
Thorgeirsson
S S
SS
Di Fiore
P P
PP
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D029721:Drosophila Proteins; D015180:Electrophoresis, Gel, Two-Dimensional; D066246:ErbB Receptors / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D066246:ErbB Receptors; D051419:Paxillin; D010750:Phosphoproteins; D011505:Protein-Tyrosine Kinases; D011506:Proteins; D011518:Proto-Oncogene Proteins; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; D018719:Erb-b2 Receptor Tyrosine Kinases; C496062:Pxn protein, mouse; C416649:Ret protein, Drosophila; C494999:Ret protein, mouse