Couples signals from receptor and cytoplasmic tyrosine kinases to the Ras signaling pathway. Plays a role in the inner ear and in hearing (PubMed:30610177). 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. Localizes at the presynaptic terminal. The disease is caused by variants affecting the gene represented in this entry. Belongs to the GRB2/sem-5/DRK family.