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. Homodimerization could regulate efficiency of zinc transport. Belongs to the cation diffusion facilitator (CDF) transporter (TC 2.A.4) family. SLC30A subfamily.