| Background |
p130 Cas (Crk-associated substrate) is a docking protein containing multiple protein-protein interaction domains. The amino-terminal SH3 domain may function as a molecular switch regulating CAS tyrosine phosphorylation, as it interacts with focal adhesion kinase (FAK) and the FAK-related kinase PYK2 as well as the tyrosine phosphatases PTP-1B and PTP-PEST The carboxy-terminal Src binding domain (SBD) contains a proline-rich motif that mediates interaction with the SH3 domains of Src-family kinases (SFKs) and a tyrosine phosphorylation site (Tyr668 and/or Tyr670) that can promote interaction with the SH2 domain of SFKs The p130 Cas central substrate domain, the major region of tyrosine phosphorylation, is characterized by 15 tyrosines present in Tyr-X-X-Pro (YXXP) motifs, including Tyr165, 249, and 410. When phosphorylated, most YXXP motifs are able to serve as docking sites for proteins with SH2 or PTB domains including adaptors, C-Crk, Nck, and inositol 5'-phosphatase 2 (SHIP2) The tyrosine phosphorylation of p130 Cas has been implicated as a key signaling step in integrin control of normal cellular behaviors including motility, proliferation, and survival. Aberrant Cas tyrosine phosphorylation may contribute to cell transformation by certain oncoproteins.
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