title: c-Src phosphorylates epidermal growth factor receptor on tyrosine 845.
abstract: In the previous study [Sato et al. (1995) Biochem. Biophys. Res. Commun. 210, 844-851], we found that c-Src was associated with epidermal growth factor (EGF) receptor and activated upon EGF treatment in A431 cells. In the present study, we investigated the phosphorylation of EGF receptor by c-Src in the c-Src-EGF receptor complex. We have focused our attention to tyrosine residue 845 (Y845) of EGF receptor as a candidate for the phosphorylation site. A synthetic peptide containing Y845, named Y845 peptide, which corresponds to residue 837 to 856 of EGF receptor, was found to be phosphorylated by c-Src and used to provide the standard phosphopeptide. In addition to the autophosphorylated peptide of 25 kDa, a phosphopeptide of 7 kDa was detected in the cyanogen bromide-digested fragments of the c-Src-associated EGF receptor phosphorylated in vitro in an EGF-dependent manner. In phosphopeptide mapping, tryptic digest of the 7-kDa phosphopeptide was shown to co-migrate with that of the phosphorylated Y845 peptide. The 7-kDa phosphopeptide was found to be phosphorylated exclusively on tyrosine. These results suggest that c-Src can phosphorylate EGF receptor on Y845 in an EGF-dependent manner. Furthermore, we confirmed that the same site of the c-Src-associated EGF receptor was phosphorylated in EGF-treated A431 cells.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D003488:Cyanogen Bromide; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000032:analysis; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D013379:Substrate Specificity; D014357:Trypsin; D014443:Tyrosine
chemical_list: D010446:Peptide Fragments; D010748:Phosphopeptides; D019000:Phosphotyrosine; D014443:Tyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D016392:Proto-Oncogene Proteins pp60(c-src); D014357:Trypsin; D003488:Cyanogen Bromide