The products of the genes cnrA, cnrB, and cnrC are likely to form a membrane-bound protein complex catalyzing an energy-dependent efflux of Ni(2+) and Co(2+). The mechanism of action of the CnrCBA complex may be that of a proton/cation antiporter. By nickel. Belongs to the resistance-nodulation-cell division (RND) (TC 2.A.6) family.