Figure 5.

Recombinant hexahistidine-tagged XAB1 hydrolyzes GTP but not ATP. (A) Affinity purified His-XAB1 (In) was loaded onto a Mini Q column. The bound proteins were eluted with a linear gradient of KCl and fractions were analyzed by SDS–polyacrylamide gel electrophoresis and Coomassie blue staining. (B) Samples eluted from the Mini Q column were assayed for GTPase activity. Mini Q-purified His-XAB1 (0.1 mg/ml) was assayed for GTPase (C) or ATPase (D) activity. Incubations were carried out for 0, 15 and 30 min. Thin layer chromatography was performed with a solution containing 1.6 M LiCl (B) or 1 M acetic acid and 1 M LiCl (C and D). The positions of GTP, GDP and ATP are indicated.