An efflux transporter able to transport Hoechst 33342, ethidium bromide, doxorubicin and a number of other drugs in vitro into inside out vesicles. The endogenous substrate is unknown. It has been suggested that NBD dimerization induced by ATP-binding causes a large conformational change responsible for substrate translocation (PubMed:18215075). Transmembrane domains (TMD) form a pore in the inner membrane and the ATP-binding domain (NBD) is responsible for energy generation (Probable). 50% inhibited by vanadate; it has been suggested that vanadate fully inhibits the dimer but not the monomer (PubMed:15766260). Activated by 15 uM reserpine then inhibited by higher concentrations. Reconstituted in proteoliposomes (PubMed:12968023). Optimum pH is 8.0. Homodimer. In BmrA the ATP-binding domain (NBD) and the transmembrane domain (TMD) are fused. This is considered to be a half-size transporter that undergoes homodimerization to be functional. Not essential. Belongs to the ABC transporter superfamily.