Mediates a low-level metal ion resistance, probably by efflux of cations from the cytoplasm into the periplasm. Also mediates resistance to cobalt, cadmium and zinc via regulation of the Czc system. May repress expression of the Czc system by an export of the inducing cations. Binds and transports zinc. Can also bind cobalt, copper and nickel. Efflux is inhibited by FCCP. Most highly expressed when the upstream czcCBA transcript is not induced. Mutant is impaired in metal sensing. Deletion leads to partially constitutive expression of the Czc system due to an increased transcription of the czcCBA genes. Belongs to the cation diffusion facilitator (CDF) transporter (TC 2.A.4) family. SLC30A subfamily.