Son Of Sevenless Homolog 2 (SOS2)

The Drosophila 'Son of sevenless' (Sos) gene was isolated by Simon et al. (1991) in a screen to identify components of the regulatory pathway between tyrosine kinase and the RAS G-proteins . Sos acts by catalyzing the exchange of GDP for GTP on ras.

Bowtell et al. (1992) isolated 2 cDNAs, designated Sos1 and Sos2, from a mouse eye library by screening with a probe from the Drosophila Sos gene. The partial Sos2 cDNA encoded a predicted 1297-amino acid protein which was 67% identical to the mouse Sos1 sequence. Both Sos1 and Sos2 had an overall amino acid identity of 45% with the Drosophila gene product. Northern blots showed that both genes are expressed in a wide variety of tissues and cell lines.