Zinc transporter 7

Intracellular zinc homeostasis is regulated by zinc-binding proteins and zinc transporters (Rink et al. 2007). The zinc transporters are encoded by two SLC ("solute linked carrier") gene families:

• Members of the SLC39 family (Zip, "Zrt- and Irt-like proteins") increase the cytoplasmic zinc level by zinc uptake.
• Members of the SLC30 family (ZnT, zinc transporter/exporter; CDF family, cation diffusion facilitator) lower intracellular zinc concentrations by transporting zinc out of the cell or into vesicular structures. So far, 15 Zips and 9 ZnTs have been detected in various human cells.

Like ZnT-5 and ZnT-6, the zinc transporter ZnT-7 mediates the transport of zinc from the cytoplasm into the trans-Golgi apparatus as well as into the vesicular compartment (Suzuki et al 2005). After zinc treatment, expression in THP-1 cells increases, whereas zinc deficiency leads to a reduction (Cousins et al 2003). In contrast, zinc supplementation in HeLa cells has no effect on expression, whereas zinc depletion induces it (Devergnas et al 2004).

1. Devergnas S et al (2004) Differential regulation of zinc efflux transporters ZnT-1, ZnT-5 and ZnT-7 gene expression by zinc levels: a real-time RT-PCR study. Biochem. Pharmacol 68: 699-709.
2. Kambe T et al (2004) Overview of mammalian zinc transporters. Cell Mol Life Sci 61: 49-68.
3. Overbeck S (2008) The regulation of zinc transporters and their influence on intracellular zinc homeostasis in leukocytes. Dissertation. Publication server of RWTH Aachen University
4. Rink L et al (2001) Extracellular and immunological actions of zinc. Biometals 14: 367-383.
5. Rink L et al (2007) Zinc homeostasis and immunity. Trends Immunol 28: 1-4.
6. Suzuki T et al (2005) Zinc transporters, ZnT5 and ZnT7, are required for the activation of alkaline phosphatases, zinc-requiring enzymes that are glycosylphosphatidylinositol-anchored to the cytoplasmic membrane. J Biol Chem 280: 637-643.