Submitted to: Journal of Biological Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/4/2005
Publication Date: 2/10/2005
Citation: Huang, L., Kirschke, C.P., Zhang, Y., Yu, Y. 2005. ZIP7 GENE (SLC39A7) ENCODES A ZINC TRANSPORTER INVOLVED IN ZINC HOMEOSTASIS OF THE GOLGI APPARATUS. Journal of Biological Chemistry 280(15):15456-15463, 2005. Interpretive Summary: This manuscript describes the characterization of a mammalian member of the ZIP (ZRT1 and IRT1-like protein) family, ZIP7. In the mammalian cell, the ZIP7 protein was localized on the membrane of the Golgi apparatus. The Golgi apparatus is a membrane-bound structure that is important in protein modifications, such as adding sugar motifs into the proteins, and in packaging proteins and other molecules, such as minerals, for transport elsewhere in the cell. It is demonstrated in this manuscript that ZIP7 is a functional zinc transporter that acts in the mobilization of zinc out of the Golgi apparatus which leads to decrease of the level of accumulated zinc in the cell.
Technical Abstract: It has been suggested that ZIP7 (Ke4, Slc39A7) belongs to the ZIP zinc transporter family. Transient expression of the V5 tagged human ZIP7 fusion protein in CHO cells led to elevation of the cytoplasmic zinc level. However, the precise function of ZIP7 in cellular zinc homeostasis is not clear. Here we report that the ZIP7 gene is ubiquitously expressed in human and mouse tissues. The endogenous ZIP7 was associated with the Golgi apparatus and was capable of transporting zinc ions from the Golgi apparatus into the cytoplasm of the cell. Moreover, by using the yeast mutant strain 'zrt3 that was defective in release of stored zinc from vacuoles, we found that the ZIP7 protein was able to decrease the level of accumulated zinc and in the meantime to increase the nuclear/cytoplasmic labile zinc level in the ZIP7 expressing zrt3 mutant cells. Our study demonstrates that ZIP7 is a functional zinc transporter that acts transporting zinc from the Golgi apparatus to the cytoplasm of the cell.