passages.id: split_8_test_1630_passage
passages.type: progene_text
passages.text: Furthermore , Grb2 bound to tyrosine - phosphorylated FRS2 through its SH2 domain interacts primarily via its carboxyl - terminal SH3 domain with a proline - rich region in Gab1 and via its amino - terminal SH3 domain with the nucleotide exchange factor Sos1 .