SOS1 Protein, Human, Recombinant

SOS1, also known as son of sevenless homolog 1, is a Ras and Rac guanine nucleotide exchange factor (GEF). SOS1 binds and activates GDP-bound RAS family proteins at its catalytic binding site and in this way promotes exchange of GDP for GTP. Depletion of SOS1 or specific genetic inactivation of its GEF function has been shown to decrease the survival of tumor cells harboring a KRAS mutation (1).

The recombinant protein (amino acids 563-1049 of human SOS1) contains two domains, REM (Ras Exchanger Motif) and CDC25 (cell division cycle 25). CDC25 activates Ras and promotes nucleotide exchange on Ras proteins (2). The REM domain contains an activating allosteric site which binds Ras-GTP leading to additional stimulation of the CDC25 domain and potentiating the Ras-GTP exchange stimulated by SOS1.

The human SOS1 (Lys563-Thr1049) fragment with a polyhistidine tag at the C-terminus was expressed in E. coli.

Sequence of recombinant human SOS1 protein:

MKEEQMRLPSADVYRFAEPDSEENIIFEENMQPKAGIPIIKAGTVIKLIERLTYHMYADPNFVRTFL

TTYRSFCKPQELLSLIIERFEIPEPEPTEADRIAIENGDQPLSAELKRFRKEYIQPVQLRVLNVCRHW

VEHHFYDFERDAYLLQRMEEFIGTVRGKAMKKWVESITKIIQRKKIARDNGPGHNITFQSSPPTV

EWHISRPGHIETFDLLTLHPIEIARQLTLLESDLYRAVQPSELVGSVWTKEDKEINSPNLLKMIRHTT

NLTLWFEKCIVETENLEERVAVVSRIIEILQVFQELNNFNGVLEVVSAMNSSPVYRLDHTFEQIPSR

QKKILEEAHELSEDHYKKYLAKLRSINPPCVPFFGIYLTNILKTEEGNPEVLKRHGKELINFSKRRKV

AEITGEIQQYQNQPYCLRVESDIKRFFENLNPMGNSMEKEFTDYLFNKSLEIEPRNPKPLPRFPKK

YSYPLKSPGVRPSNPRPGTLEHHHHHH*

Catalog# SOS1-301

Applications

• Study inhibitors of SOS1 GTP exchange activity
• Identification of SOS1 binding proteins
• Study of SOS1 GEF activity with different GTPases

Storage buffer: 20 mM HEPES, pH 7.5, 100 mM NaCl, 1 mM 2-mercaptoethanol, 20% Glycerol. 
Concentration: 1.0 - 2.0 mg/mL by A280 (please see specific lot number).

Molecular weight: ~58.3 kDa
Purity: >90% by Coomassie staining 
Storage is recommended at -20°C for longer periods of time. 

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This product is for laboratory research use only.

References

1. Jeng, H. et al. SOS-mediated cross-activation of wild-type Ras by oncogenic Ras is essential for tumorigenesis. Nat Commun 2012; 3:1168.
2. Pierre, S. et al. Understanding SOS (Son of Sevenless). Biochem Pharmacol. 2011 Nov 1;82(9):1049-56.