hRMI1 specifically stimulates the hTOPO IIIα component of dissolution reactions. (A Upper) Dissolution reactions containing fixed concentrations of BLM and hRMI1 as indicated by the black and white bars, respectively, and a 2-fold dilution series of hTOPO IIIα (highest concentration of 40 nM, indicated by the gray triangles). The positions of DHJ and the detectable dissolution product are indicated on the left. (A Lower) Quantification of the dissolution product in lanes 2–6 (−hRMI1) and lanes 9–13 (+hRMI1) as a function of hTOPO IIIα concentration. (B Upper) Dissolution reactions containing fixed concentrations of hTOPO IIIα and hRMI1, as indicated by the gray and white bars, respectively, and a 2-fold dilution series of BLM (highest concentration of 1.5 nM, indicated by black triangles). (B Lower) Quantification of the dissolution product in lanes 2–6 (−hRMI1) and lanes 9–13 (+hRMI1) as a function of BLM concentration.