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 outer membrane factor (OMF) (TC 1.B.17) family.