Zinc networks: the cell-specific compartmentalization of zinc for specialized functions

Zinc (Zn2+) is the most abundant trace element in cells and is essential for a vast number of catalytic, structural, and regulatory processes. Mounting evidence indicates that like calcium (Ca2+), intracellular Zn2+ pools are redistributed for specific cellular functions. This occurs through the regulation of 24 Zn2+ transporters whose localization and expression is tissue and cell specific. We propose that the complement and regulation of Zn2+ transporters expressed within a given cell type reflects the function of the cell itself and comprises a 'Zn2+ network.' Importantly, increasing information implicates perturbations in the Zn2+ network with metabolic consequences and disease. Herein, we discuss our current understanding of Zn2+ transporters from the perspective of a Zn2+ network in four specific tissues with unique Zn2+ requirements (mammary gland, prostate, pancreas, and brain). Delineating the entire Zn2+ transporting network within the context of unique cellular Zn2+ needs is important in identifying critical gaps in our knowledge and improving our understanding of the consequences of Zn2+ dysregulation in human health and disease.