GRB2 (growth factor receptor-bound protein 2) is a critical signaling molecule that regulates the Ras pathway by linking tyrosine kinases to the Ras guanine nucleotide releasing protein Sos (son of sevenless), which converts Ras to the active GTP-bound state. It is ubiquitously expressed in all tissues throughout development and is important in cell cycle progression, motility, morphogenesis and angiogenesis []. In lymphocytes, GRB2 is associated with antigen receptor signaling components []. GRB2 contains an N-terminal SH3 domain, a central SH2 domain and a C-terminal SH3 domain. This entry represents the SH3 domain found at the C terminus of GRB2. This SH3 domain has been found to bind to Gab2 (Grb2-associated binder 2) through epitopes containing RxxK motifs, as well as to the proline-rich C terminus of FGRF2 [, ].
