Zinc ion transporter mediating zinc import from cytoplasm potentially into the endocytic compartment (By similarity). Controls zinc deposition in milk (By similarity). Zn(2+)(in) = Zn(2+)(out) Homodimerization could regulate efficiency for zinc transport. Enriched in vesicles within the basal region of epithelial cells. Belongs to the cation diffusion facilitator (CDF) transporter (TC 2.A.4) family. SLC30A subfamily.