Mammalian Zinc Transport, Trafficking, and Signals

Structural, catalytic, and regulatory functions of zinc in biology continue to be defined. The number of genes coding for proteins with zinc-binding domains is conservatively estimated at 3% of the human genome but possibly is as much as 10% (1, 2). Zinc utilization in abundant, yet diverse, applications illustrates why organisms have evolved specific pathways to homeostatically regulate availability of this essential micronutrient at specific cellular sites through an array of transporters. Animals regulate zinc gain and loss efficiently. In humans, about 1% of the total body zinc content is replenished daily by the diet (3). This is accomplished principally by tight control of two systems, absorption from…