An adaptor protein (growth factor receptor bound protein 2, 217 aa), the mammalian homologue of Caenorhabditis elegans Sem-5 and Drosophila Drk that links the cytoplasmic domain of growth factor receptors to downstream elements of the signalling pathway through its SH2 and SH3 domains. The SH2 domain binds autophosphorylated residues on the growth factor receptor's cytoplasmic tail and the SH3 domain binds nucleotide exchange factors such as sos1. Grb2-associated binder-1 (gab-1, 694 aa) binds to Grb-2 and has homology with IRS-1 (insulin receptor substrate-1). It is a substrate for the EGF receptor and may integrate signals from different receptors into the control of cellular responses. Grb2-related adaptor protein-1 (GRAP1; 217 aa) interacts in vitro with c-kit (stem cell factor receptor) and the erythropoietin receptor, linking them to the ras signalling pathway. Grb2-related adaptor protein-2 (GRAP2, GADS, 330 aa) is another of the Grb2/Sem5/Drk family and reportedly involved in leucocyte-specific protein tyrosine kinase signalling.
Subjects: Medicine and Health — Chemistry.