Links T-cell receptor activation signal to phospholipase C-gamma-1, GRB2 and phosphatidylinositol 3-kinase. Preferentially expressed by lymphocytes in lymph node and spleen. Tyrosine-phosphorylated upon T-cell activation. The tyrosine phosphorylation site is multifunctional and may associate with the SH2 domains of phospholipase C-gamma-1, GRB-2, and PI3-K upon T-cell receptor activation. Belongs to the SH2B adapter family.