CzcA and CzcB together would act in zinc efflux nearly as effectively as the complete czc efflux system (CzcABC). The CzcB protein is thought to funnel zinc cations to the CzcA transport protein. May be anchored in the inner membrane, cross the periplasm and contact the outer membrane as proposed for membrane fusion proteins. By zinc, cadmium and cobalt (zinc being the best and cobalt being the worst inducer). In the presence of 2 mM Cd(2+) or 4-10 mM Zn(2+) up to 99% of the metal is removed from the culture supernatant and is sequestered via bioprecipitation. Additionally Cu(2+), Co(2+), Ni(2+), Pb(2+), Y(3+) and Ge(4+) can also be removed from culture supernatants, although it is not clear which efflux system is responsible for all these substrates (PubMed:7766206). Belongs to the membrane fusion protein (MFP) (TC 8.A.1) family.