GEF-H1 contains an AID. (A) Domain organization and sequence alignment of GEF-H1 and Vav1, with AID of Vav1 shown in purple and the central Tyr residues in red. Secondary structure prediction (Ss pred) shown for GEF-H1 (gray). (B) RhoA exchange activity of recombinantly expressed GEF-H1 constructs with truncation or mutation of the AID. Red arrow indicates GEF addition. Curves show average of two independent experiments, and error bars display SD.