Interacts with SLP-76 to regulate NF-AT activation. Binds to tyrosine-phosphorylated shc. Interacts with phosphorylated LAT and LAX1 upon TCR activation. Interacts with SHB. Interacts with PTPN23 (By similarity). Interacts with phosphorylated LIME1 upon TCR activation. Belongs to the GRB2/sem-5/DRK family.