SLC30A4 and Alzheimer disease: In addition to alterations in ZNT1 expression, ZNT4 and ZNT6 protein levels are upregulated in late AD.37 The ZNT4 and ZNT6 proteins transport zinc into the lysosomal and trans-golgi compartments and it has been hypothesized that an upregulation of ZNT4 and ZNT6 would allow excess zinc to be removed from the cytoplasm before doing any harm.55 On the other hand, upregulation of ZNT4 and ZNT6 might also reflect the relative increase in glial cells in late AD.