Novel Recognition Motif on Fibroblast Growth Factor Receptor Mediates Direct Association and Activation of SNT Adapter Proteins

Fibroblast growth factors (FGFs) stimulate tyrosine phosphorylation of a membrane-anchored adapter protein, FRS2/SNT-1, promoting its association with Shp-2 tyrosine phosphatase and upstream activators of Ras. Using the yeast two-hybrid protein-protein interaction assay, we show that FRS2/SNT-1 and a newly isolated SNT-2 protein directly bind to FGF receptor-1 (FGFR-1). A juxtamembrane segment of FGFR-1 and the phosphotyrosine-binding domain of SNTs are both necessary and sufficient for interaction in yeast and in vitro , and FGFR-mediated SNT tyrosine phosphorylation in vivo requires these segments of receptor and SNT. Our findings establish SNTs as direct protein links between FGFR-1 and multiple downstream pathways. The SNT binding motif of FGFR-1 is distinct from previously described phosphotyrosine-binding domain recognition motifs, lacking both tyrosine and asparagine residues.