INTERACTIONS OF FLT-1 AND KDR WITH PHOSPHOLIPASE-C-GAMMA - IDENTIFICATION OF THE PHOSPHOTYROSINE BINDING-SITES

Vascular endothelial cell growth factor interacts with the receptor ty rosine kinases Flt-1 and KDR/Flk-1. We report that both receptors bind to PLC gamma and display specificity for the N-SH2 over the C-SH2 dom ain. Extensive site-directed mutagenesis of Flt-1 reveals that the jux ta-membrane Y794, and the carboxyl terminal Y1169, are two major sites of interaction. Amino acids in the +1,+2 and +3 positions following t hese tyrosines are LSI and IPI, respectively. Peptide maps generated f rom wild type and mutant Flt-1 confirms that these residues are autoph osphorylated. As predicted, mutagenesis of the analogous amino acids i n KDR, positions Y801F and Y1175F, which lie in contexts YLSI and YIVL , respectively, reduced interactions of PLC gamma with this receptor. We conclude that both Flt-1 and KDR have the potential to signal throu gh PLC gamma via phosphotyrosine residues located in juxta-membrane an d carboxyl tail regions. (C) 1997 Academic Press.