SUC1-ASSOCIATED NEUROTROPHIC FACTOR TARGET (SNT) PROTEIN IS A MAJOR FGF-STIMULATED TYROSINE-PHOSPHORYLATED 90-KDA PROTEIN WHICH BINDS TO THE SH2 DOMAIN OF GRB2

In Swiss 3T3 fibroblasts, basic fibroblast growth factor (bFGF) stimul ates the unique tyrosine phosphorylation of a protein complex around 9 0 kDa, as ascertained by high resolution 2-D PAGE and anti-phosphotyro sine blotting. The majority of this complex consists of the protein(s) designated previously as SNT (suc1-associated neurotrophic factor tar get). Tyrosine phosphorylated SNT binds to both p13(suc1) protein and the SH2 domain of Grb2. Binding of SNT to Grb2 is likely to be mediate d through the consensus binding motif, pYXN, on SNT. The binding of SN T to p13(suc1) is independent of the pYXN motif. Tyrosine phosphorylat ed SNT is localised in the plasma membrane where it could form a compl ex with Grb2 and Sos, enabling the initiation of a novel FGF-specific signalling pathway. (C) 1996 Academic Press, Inc.