DI1020011 SH2 domain of p56lck in complex with a phosphotyrosyl peptide derived from polyomavirus antigen. 1lcj X-ray 1.80 Hamster polyomavirus / Homo sapiens Inferred from motif 1.00E-09 7680435 7680435 Eck MJ, Shoelson SE, Harrison SC Nature 1993 6415 362 87-91 The Src homology-2 (SH2) domains are modules of about 100 amino-acid residues that are found in many intracellular signal-transduction proteins. They bind phosphotyrosine-containing sequences with high affinity and specificity, recognizing phosphotyrosine in the context of the immediately adjacent polypeptide sequence. The protein p56lck (Lck) is a Src-like, lymphocyte-specific tyrosine kinase. A phosphopeptide library screen has recently been used to deduce an 'optimal' binding sequence for the Lck SH2 domain. There is selectivity for the residues Glu, Glu and Ile in the three positions C-terminal to the phosphotyrosine. An 11-residue phosphopeptide derived from the hamster polyoma middle-T antigen, EPQpYEEIPIYL, binds with an approximately 1 nM dissociation constant to the Lck SH2 (ref. 17), an affinity equivalent to that of the tightest known SH2-phosphopeptide complex. We report here the high-resolution crystallographic analysis of the Lck SH2 domain in complex with this phosphopeptide. Recent crystallographically derived structures of the Src SH2 domain in complex with low-affinity peptides, which do not contain the EEI consensus, and NMR-derived structures of unliganded Abl (ref. 19) and p85 (ref. 20) SH2 domains have revealed the conserved fold of the SH2 domain and the properties of a phosphotyrosine binding pocket. Our high-affinity complex shows the presence of a second pocket for the residue (pY + 3) three positions C-terminal to the phosphotyrosine (pY). The peptide is anchored by insertion of the pY and pY + 3 side chains into their pockets and by a network of hydrogen bonds to the peptide main chain. In the low-affinity phosphopeptide/Src complexes, the pY + 3 residues do not insert into the homologous binding pocket and the peptide main chain remains displaced from the surface of the domain. GO:0016032 viral process GO:0016020 membrane No modifications of the original PDB file. 2 SH2 B Middle T antigen Disordered Hamster polyomavirus EPQYEEIPIYL 204 324 Y phosphotyrosine 11 P03079 321 331 2.7% UniRef90_P03079 321 331 secondary structure beta 325 325 A Tyrosine-protein kinase Lck Ordered Homo sapiens MANSLEPEPWFFKNLSRKDAERQLLAPGNTHGSFLIRESESTAGSFSLSVRDFDQNQGEVVKHYKIRNLDNGGFYISPRITFPGLHELVRHYTNASDGLCTRLSRPCQT 109 P06239 118 226 21.4% UniRef90_P06239 119 226 secondary structure beta 128 128 secondary structure helix 134 141 secondary structure beta 151 155 secondary structure beta 163 171 secondary structure beta 175 186 secondary structure beta 190 192 secondary structure beta 199 199 secondary structure helix 202 211 secondary structure beta 223 223 pfam PF00017.21 SH2 127 209 B The protein region involved in the interaction contains a known functional linear motif (LIG_SH2_SRC). A The SH2 domain involved in the interaction is known to adopt a stable structure in isolation (see Pfam domain PF00017). A solved monomeric structure of the domain is represented by PDB ID 1ijr.