Zinc ion transporter mediating the import of zinc from cytoplasm into synaptic vesicles and participating to cellular zinc ion homeostasis in the brain. Zn(2+)(in) = Zn(2+)(out) Homodimer; dityrosine-linked. Homodimerization seems specific of the human protein and enhances the zinc transport efficiency. Homodimerization through dityrosine bonds is stimulated by oxidative stress. Belongs to the cation diffusion facilitator (CDF) transporter (TC 2.A.4) family. SLC30A subfamily.