Once recruited to the membrane in response to c-Kit stimulation, Son of sevenless (SOS1) activates the small GTPase protein RAS. SOS1 is a dual specificity guanine nucleotide exchange factor (GEF) that regulates both Ras and Rho family GTPases. SOS1 activates RAS by binding, which induces a conformational change that causes the exchange of GDP for GTP. RAS proteins are membrane-bound GTPases that regulate crucial cellular processes such as growth, proliferation and differentiation. Active RAS-GTP stimulates multiple effector proteins such as RAF-1, which induce a variety of cellular responses including initiation of mitogen activated protein kinase (MAPK) cascade signaling.
Reber, L, Da Silva, CA, Frossard, N
Miyazawa, K, Hendrie, PC, Mantel, C, Wood, K, Ashman, LK, Broxmeyer, HE
Roskoski, R Jr
Duronio, V, Welham, MJ, Abraham, S, Dryden, P, Schrader, JW
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