Divalent metal cation transporter which exports Zn(2+), Cd(2+) and possibly Fe(2+) (PubMed:14960568, PubMed:15549269, PubMed:16049012, PubMed:16790427, PubMed:19749753). May be involved in zinc and iron detoxification by efflux (PubMed:15549269, PubMed:19749753). In vitro, can also bind, but probably not transport, Hg(2+), Co(2+), Ni(2+), Mn(2+), Ca(2+) and Mg(2+) (PubMed:14960568, PubMed:16049012, PubMed:16790427). H(+)(out) + Zn(2+)(in) = H(+)(in) + Zn(2+)(out) Cd(2+)(in) + H(+)(out) = Cd(2+)(out) + H(+)(in) Fe(2+)(in) + H(+)(out) = Fe(2+)(out) + H(+)(in) Cytoplasmic zinc binding may trigger movements of two electrically repulsive cytoplasmic domains and reorient transmembrane helices, thereby modulating coordination geometry of the active site for zinc transport. It may modulate activity in response to cytoplasmic metal fluctuations. Homodimer (PubMed:15258151, PubMed:17717154, PubMed:19749753). The subunits are held together in a parallel orientation through zinc binding at the interface of the cytoplasmic domains (PubMed:17717154, PubMed:19749753). Induced by iron and zinc. The two transmembrane domains of the dimer swing out to yield a Y-shaped structure (PubMed:17717154, PubMed:19749753). In each protomer, the cytoplasmic domain adopts a metallochaperone-like protein fold (PubMed:17717154, PubMed:19749753). Each protomer contains three zinc-binding sites: a tetrahedral active Zn(2+) binding site for zinc transport, which is located toward the center of the transmembrane domain, and two cytoplasmic Zn(2+) binding sites that may serve as zinc sensors and regulate activity (PubMed:17717154, PubMed:19749753). Asp-49 and Asp-157 are required for both metal binding and transport process (PubMed:16049012, PubMed:16790427). Asp-49 is a selective binding residue for Zn(2+), Cd(2+) and Fe(2+) (PubMed:16790427). Asp-157 is a highly specific coordination residue for Zn(2+) and Cd(2+), but not for Hg(2+) and Fe(2+) (PubMed:16049012). Belongs to the cation diffusion facilitator (CDF) transporter (TC 2.A.4) family. FieF subfamily.