Promotes excretion of zinc from intestinal cells into the intestinal lumen in response to increased dietary zinc (PubMed:23717214). Involved in cadmium resistance, possibly by promoting its transport from cells (PubMed:15256590). Involved in resistance to B.thuringiensis pore-forming toxin Cry5B downstream of the sek-1 and pmk-1 MAPK kinase pathway (PubMed:15256590). Isoform a: Expressed in the hypodermis and the intestine. Isoform b: Expressed in the intestine, head neurons, seam cells, hypodermis, and the vulva. By B.thuringiensis pore-forming toxin Cry5B (PubMed:15256590). Isoform a: Not induced by zinc. Isoform b: Induced by zinc specifically in intestinal cells (PubMed:23717214). RNAi-mediated knockdown causes hypersensitivity to low, chronic doses of the B.thuringiensis pore-forming toxin Cry5B and heavy metal Cd(2+) exposure. Belongs to the cation diffusion facilitator (CDF) transporter (TC 2.A.4) family. SLC30A subfamily.