GRB2-1 is an adaptor protein for the RAS guanyl nucleotide exchange factor SOS1. GRB2-1, through association with activated receptor tyrosine kinases, such as MET, mediates recruitment of SOS1 to the plasma membrane. At the plasma membrane, SOS1 catalyzes guanyl nucleotide exchange on RAS proteins from GDP to GTP, resulting in RAS activation downstream of MET (Shen and Novak 1997, Besser et al. 1997).
Besser, D, Bardelli, A, Didichenko, S, Thelen, M, Comoglio, PM, Ponzetto, C, Nagamine, Y
Shen, K, Novak, RF
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