Identification of p90, a Prominent Tyrosine-phosphorylated Protein in Fibroblast Growth Factor-stimulated Cells, as 80K-H (∗)

Autor: Goh, Kee Chuan, Lim, Yoon Pin, Ong, Siew Hwa, Siak, Chia Bin, Cao, Xinmin, Tan, Yin Hwee, Guy, Graeme R.
Zdroj: Journal of Biological Chemistry; March 1996, Vol. 271 Issue: 10 p5832-5838, 7p
Abstrakt: 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.
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