Removal of the GST tag with thrombin protease did not alter the ability of PX/PH domains to catalyze the exchange reaction.
A, shown is SDS-PAGE of the purified proteins stained with Gel-code Blue showing GST-free PX, PH, and PXPH proteins at the expected molecular weights. Relative GDP dissociation (B) and GTP binding (C) of Rac2 in the presence of recombinant GST-free PX, PH, or PXPH (2 μm each) is shown. Rac2 alone (white) was used as a control.