Identification of tyrosines 154 and 307 in the extracellular domain and 653 and 766 in the intracellular domain as phosphorylation sites in the heparin-binding fibroblast growth factor receptor tyrosine kinase (flg). |
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| Authors: | J. Hou K. McKeehan M. Kan S. A. Carr M. J. Huddleston J. W. Crabb W. L. McKeehan |
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| Affiliation: | W. Alton Jones Cell Science Center, Lake Placid, New York 12946. |
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| Abstract: | Four tyrosine residues have been identified as phosphorylation sites in the tyrosine kinase isoform of the heparin-binding fibroblast growth factor receptor flg (FGF-R1). Baculoviral-insect cell-derived recombinant FGF-R1 was phosphorylated and fragmented with trypsin while immobilized on heparin-agarose beads. Phosphotyrosine peptides were purified by chromatography on immobilized anti-phosphotyrosine antibody and analyzed by Edman degradation and electrospray tandem mass spectrometry. Tyrosine residue 653, which is in a homologous spatial position to major autophosphorylation sites in the catalytic domain of the src and insulin receptor kinases, is the major intracellular FGF-R1 phosphorylation site. Residue 766 in the COOH-terminus outside the kinase domain is a secondary site. Tyrosine residues 154 and 307, which are in the extracellular domain of transmembrane receptor isoforms and are in an unusual sequence context for tyrosine phosphorylation, were also phosphorylated. |
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| Keywords: | growth factors oncogenes signal transduction |
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