A novel gene involved in zinc transport is deficient in the lethal milk mouse

We have identified the gene responsible for the inherited zinc deficiency in the lethal milk (lm) mouse. The gene, here designated Znt4, encodes a 430-amino-acid protein that is homologous to two proteins, ZnT2 and ZnT3, responsible for sequestration of zinc into endosomal/lysosomal compartments and synaptic vesicles, respectively. We show that the Znt4 gene confers zinc resistance to a zinc-sensitive yeast strain and that it is abundantly expressed in the mammary epithelia and brain. The lethal milk mutant has a nonsense mutation at arginine codon 297 in the Znt4 gene.