SPECIFIC MOTIFS RECOGNIZED BY THE SH2 DOMAINS OF CSK, 3BP2, FPS FES, GRB-2, HCP, SHC, SYK, AND VAV

Src homology 2 (SH2) domains provide specificity to intracellular sign aling by binding to specific phosphotyrosine (phospho-Tyr)-containing sequences. We recently developed a technique using a degenerate phosph opeptide library to predict the specificity of individual SH2 domains (src family members, Abl, Nck, Sem5, phospholipase C-gamma, p85 subuni t of phosphatidylinositol-3-kinase, and SHPTP2 (Z. Songyang, S. E. Sho elson, M. Chaudhuri, G. Gish, T. Pawson, W. G. Haser, F. King, T. Robe rts, S. Ratnofsky, R. J. Lechleider, B. G. Neel, R. B. Birge, J. E. Fa jardo, M. M. Chou, H. Hanafusa, B. Schaffhausen, and L. C. Cantley, Ce ll, 72:767-778, 1993). We report here the optimal recognition motifs f or SH2 domains from GRB-2, Drk, Csk, Vav, fps/fes, SHC, Syk (carboxy-t erminal SH2), 3BP2, and HCP (amino-terminal SH2 domain, also called PT P1C and SHPTP1). As predicted, SH2 domains from proteins that fall int o group I on the basis of a Phe or Tyr at the betaD5 position (GRB-2, 3BP2, Csk, fps/fes, Syk C-terminal SH2) select phosphopeptides with th e general motif phospho-Tyr-hydrophilic (residue)-hydrophilic (residue )-hydrophobic (residue). The SH2 domains of SHC and HCP (group III pro teins with Ile, Leu, or Cys at the betaD5 position) selected the gener al motif phospho-Tyr-hydrophobic-Xxx-hydrophobic, also as predicted. V av, which has a Thr at the betaD5 position, selected phospho-Tyr-Met-G lu-Pro as the optimal motif. Each SH2 domain selected a unique optimal motif distinct from motifs previously determined for other SH2 domain s. These motifs are used to predict potential sites in signaling prote ins for interaction with specific SH2 domain-containing proteins. The Syk SH2 domain is predicted to bind to Tyr-hydrophilic-hydrophilic-Leu /Ile motifs like those repeated at 10-residue intervals in T- and B-ce ll receptor-associated proteins. SHC is predicted to bind to a subgrou p of these same motifs. A structural basis for the association of Csk with Src family members is also suggested from these studies.