Multicopper oxidases (MCOs) are ubiquitous in nature and perform a wide variety of functions including pigmentation, lignin synthesis and degradation, iron homeostasis and morphogenesis. Most MCOs contain one copper ion in a type 1 site and three copper ions in a type 2/type 3 cluster. Different MCOs have been identified as laccases, ascorbate oxidases or ferroxidases. In D. melanogaster, stw (MCO2) encodes a laccase, whereas the products of Mco1 and Mco3 have been characterized as ferroxidases. (Adapted from FBrf0234915 and FBrf0222822.)