FIGURE 1.

BLM stimulates DNA strand exchange activity of RAD51 protein in the presence of Ca²⁺. A, the experimental scheme. The asterisk indicates the ³²P label. B, lanes 9–16, the kinetics of D-loop formation was initiated by addition of BLM (100 nm) and pUC19 scDNA to RAD51-ssDNA nucleoprotein filaments assembled in the presence of 0.5 mm Ca²⁺. Lanes 1–8 and 17–21, either BLM or RAD51 were substituted with their storage buffers, respectively. C, the results from B are presented as a graph. D, effect of BLM concentration on the efficiency of D-loop formation promoted by RAD51. BLM or RECQ1 (in the indicated concentrations) were added to the RAD51-ssDNA filaments formed in the presence of 0.5 mm Ca²⁺. The reactions were carried out for 15 min. The error bars in C and D indicate S.E.