Zinc transporter 3

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.

The zinc transporter 3, ZnT-3, is mainly expressed in the membrane of zinc-rich synaptic vesicles within the hippocampus and in the testis (Wenzel et al. 1997). In nerve cells, ZnT-3 transports the cytoplasmic zinc into the synaptic vesicles, from which it is released after stimulation (Wenzel et al. 1997). Little is known about the regulation of ZnT-3 expression. In the murine thymus the mRNA does not seem to react to zinc deficiency (Liuzzi and cousins, 2004).

1. Chausmer AB (1998) Zinc, insulin and diabetes. J Am Coll Nutr 17: 109-115.
2. Cousins RJ et al (2003) A global view of the selectivity of zinc deprivation and excess on genes expressed in human THP-1 mononuclear cells. Proc Natl Acad Sci USA 100: 6952-6957.
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.
7. Telford WG (1997) A reappraisal of the role of zinc in life and death decisions of cells. Proc. Soc. Exp. Biol Med 215: 229-236.
8. Wenzel HJ et all. (1997) Ultrastructural localization of zinc transporter-3 (ZnT-3) to synaptic vesicle membranes within mossy fiber boutons in the hippocampus of mouse and monkey. Proc Natl Acad Sci USA 94: 12676-12681.