Background:
Promotes ubiquitination of NF-kappa-B subunit RELA and its subsequent proteasomal degradation. Down-regulates NF-kappa-B activity. Down-regulates SOD1 activity by interfering with its homodimerization. Plays a role in copper ion homeostasis. Can bind one copper ion per monomer. May function to facilitate biliary copper excretion within hepatocytes.Tissue specificity: Ubiquitous. Highest expression in the liver, with lower expression in brain, lung, placenta, pancreas, small intestine, heart, skeletal muscle, kidney and placenta.