New work shows that activation of the Ras guanine nucleotide exchange factor SOS is dependent upon the membrane density of phosphatidylinositol-4,5-bisphosphate (PIP2) and GTP-bound Ras. These signals synergize to release the autoinhibitory DH-PH domain, while the histone domain fine-tunes SOS activation in response to PIP2.
- Greg M Findlay
- Tony Pawson