Zinc transporter 1

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 the intracellular zinc concentration 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.

ZnT-1 is ubiquitously expressed and is the only zinc transporter described so far that is known to be involved in the export of zinc through the plasma membrane in many different cells, thereby conferring resistance to high extracellular zinc concentrations (Palmiter, 2004). Zinc supplementation induces the mRNA expression of ZnT-1 in the human monocytic cell line THP-1 and in the murine breast epithelium cell line HC-11, while zinc depletion leads to a corresponding mRNA reduction (Cousins et al 2003).

1. 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.
2. Overbeck S (2008) The regulation of zinc transporters and their influence on intracellular zinc homeostasis in leukocytes. Dissertation. Publication server of RWTH Aachen University
3. Palmiter RD (2004) Protection against zinc toxicity by metallothionein and zinc transporter 1st Proc. Natl. Acad Sci U A 101: 4918-4923.