May play an important role in the control of the immune response and during pregnancy. Binds 1 zinc ion per subunit. Expressed highly in uterus during pregnancy. From the prepubertal period to day 5.5 of pregnancy is weakly expressed. From day 5.5 of pregnancy, an increase of expression is observed. At day 12.5 expression is higher. Induced by immunization in mature dendritic cells (DC), in marginal zone (MZ) metallophils, in follicular DC (FDC) and tingible body macrophages of germinal center. Down-regulated by steroid hormones and PRL.