Description
SOS1, also known as son of sevenless homolog 1, is a Ras and Rac guanine nucleotide exchange factor. This protein is composed of several important domains. The CDC25 and REM domains provide the catalytic activity of SOS1 towards Ras and the histone fold DH/PH (Dbl homology and Pleckstrin homology) domains function, in tandem, to stimulate GTP/GDP exchange for Rac. Also, binding of GTP activates Ras proteins, and subsequent hydrolysis of the bound GTP to GDP and phosphate inactivates signaling by these proteins. GTP binding can be catalyzed by guanine nucleotide exchange factors for RAS, and GTP hydrolysis can be accelerated by GTPase-activating proteins (GAPs). Recombinant human SOS1, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques