Interaction in vitro; enzyme produced as a recombinant fusion protein in bacterial system; enzyme target produced as a recombinant fusion protein in bacterial system.

trio stimulated release of [3]H-GDP from Rac1, Rac2 and mtl, but not Cdc42, Rho1 or RhoL.

GEF (guanine exchange factor) assay; enzyme target was preloaded with [3]H GDP, and trio was assayed for its ability to exchange labeled GDP for GTP.