Couples signals from receptor and cytoplasmic tyrosine kinases to the Ras signaling pathway. Plays a role in the inner ear and in hearing. Associates through its SH2 domain with ligand-activated receptors for stem cell factor (KIT) and erythropoietin (EPOR). Also forms a stable complex with the Bcr-Abl oncoprotein. GRAP is associated with the Ras guanine nucleotide exchange factor SOS1, primarily through its N-terminal SH3 domain. Interacts with phosphorylated LAT upon TCR activation. Interacts with SHB (By similarity). Localizes at the presynaptic terminal. Belongs to the GRB2/sem-5/DRK family.