Shc is an Src homology 2 (SH2) domain protein thought to be an important component of the signaling pathway leading from cell surface receptors to Ras. A new phosphotyrosine interaction (PI) domain (also known as the phosphotyrosine binding (PTB) domain) has been described in the amino terminus of Shc. The Shc PI domain binding specificity is dependent on residues lying amino-terminal to the phosphotyrosine rather than carboxyl-terminal as is seen with SH2 domains. We randomly mutagenized the Shc PTB/PI domain in an effort to identify residues in the domain crucial for interaction with phosphotyrosine-containing peptides. We then screened the mutants for binding to the tyrosine-phosphorylated carboxyl-terminal tail of the epidermal growth factor (EGF) receptor. Most striking were mutations that altered a phenylalanine residue in block 4 of the domain severely impairing PI domain function. This phenylalanine residue is conserved in all but one subfamily of PI domains that have been identified to date. Reconstitution of this phenylalanine mutation into full-length Shc created a protein unable to interact with the EGF receptor in living cells.

We report cDNA cloning and characterization of the human and mouse orthologs of the chicken YAP (Yes-associated protein) gene which encodes a novel protein that binds to the SH3 (Src homology 3) domain of the Yes proto-oncogene product. Sequence comparison between mouse, human, and chicken YAP proteins showed an inserted sequence in the mouse YAP that represented an imperfect repeat of an upstream sequence. Further analysis of this sequence revealed a putative protein module that is found in various structural, regulatory, and signaling molecules in yeast, nematode, and mammals including human dystrophin. Because one of the prominent features of this sequence motif is two tryptophans (W), we named it the WW domain (Bork, P., and Sudol, M. (1994) Trends Biochem. Sci. 19, 531-533). Since its delineation, more proteins have been shown to contain this domain, and we report here on the widespread distribution of the WW module and present a discussion of its possible function. We have also shown that the human YAP gene is well conserved among higher eukaryotes, but it may not be conserved in yeast. Its expression at the RNA level in adult human tissues is nearly ubiquitous, being relatively high in placenta, prostate, ovary, and testis, but is not detectable in peripheral blood leukocytes. Using fluorescence in situ hybridization on human metaphase chromosomes and by analyzing rodent-human hybrids by Southern blot hybridization and polymerase chain reaction amplification, we mapped the human YAP gene to chromosome band 11q13, a region to which the multiple endocrine neoplasia type 1 gene has been mapped.