title: Identification of p90, a prominent tyrosine-phosphorylated protein in fibroblast growth factor-stimulated cells, as 80K-H.
abstract: Tyrosine phosphorylation of cellular proteins occurs rapidly upon treatment of fibroblasts with acidic or basic fibroblast growth factors (aFGF, bFGF), suggesting a role for protein phosphorylation in the FGF signaling pathway. Stimulation of Swiss 3T3 cells and MRC-5 fibroblasts with bFGF results in the tyrosine phosphorylation of several proteins, of which the most prominent has been designated as p90. The phosphorylation of p90 is observed within 30 s of treating the cells with FGF but not with other growth factors. Microsequencing of p90 resolved on two-dimensional polyacrylamide gel electrophoresis indicated an N-terminal amino acid sequence which corresponded to a protein previously named as 80K-H. Polyclonal antibodies raised against the predicted C terminus of 80K-H recognized p90 on all Western blots. p90 was found to bind specifically to GRB-2-glutathione S-transferase fusion protein and to be immunoreactive with 80K-H antibody. In addition, anti-phosphotyrosine antibodies immunoprecipitated 80K-H from cell lysates of FGF-stimulated but not from control fibroblasts. The biological function of 80K-H is yet unknown. However, from this study and a previous observation of the obligatory dependence of p90 phosphorylation on FGF receptor occupation, it appears that 80K-H is involved in FGF signaling.
authors.affiliation: Signal Transduction Laboratory, Institute of Molecular and Cell Biology, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Republic of Singapore.
authors.forename: K C
authors.initials: KC
authors.lastname: Goh
authors.forename: Y P
authors.initials: YP
authors.lastname: Lim
authors.forename: S H
authors.initials: SH
authors.lastname: Ong
authors.forename: C B
authors.initials: CB
authors.lastname: Siak
authors.forename: X
authors.initials: X
authors.lastname: Cao
authors.forename: Y H
authors.initials: YH
authors.lastname: Tan
authors.forename: G R
authors.initials: GR
authors.lastname: Guy
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D004815:Epidermal Growth Factor / Q000494:pharmacology; D016220:Fibroblast Growth Factor 1 / Q000494:pharmacology*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005959:Glucosidases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008322:Mammals; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D010750:Phosphoproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D002135:Calcium-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D010982:Platelet-Derived Growth Factor; C512949:Prkcsh protein, mouse; D011993:Recombinant Fusion Proteins; D016222:Fibroblast Growth Factor 2; D016220:Fibroblast Growth Factor 1; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D005959:Glucosidases; C070368:PRKCSH protein, human