Hax-1 cDNA was amplified with specific primers (forward: 5 0 -CCAGGATCCGAGCGTCTTTGATCTTTTC CGAGGCT-3 0 , reverse: 5 0 -GCTTGTCGACTCGGGAC CGAAACCAACGTCCTA-3 0 ) and the PCR product was cloned into pET201 (a gift from Csaba Koncz, Max Planck, Institute for Plant Breeding Research, Cologne). pET201 is a non-commercial vector representing a derivative of pET vector series used for expression of recombinant proteins fused to N-terminal bacterial thioredoxin and C-terminal 6xHis tags. pET201 vector encoding for thioredoxin was used concurrently to produce thioredoxin as a control protein. Bacteria were grown at 378C to an optical density of 0.5 (OD 600 ), followed by induction with 1 mM IPTG for 4 h. Recombinant proteins were purified under native conditions according to the Qiagen protocol for His-tag protein purification. Eluted proteins were analyzed by 12% SDS-PAGE and stained by Coomassie. Western blot analysis was carried out using monoclonal anti-Hax-1 antibody (BD Bioscience). Purified proteins were stored in 50% glycerol at À208C.