This enzyme is widely distributed, especially among eukaryotes, being found in Fungi, Metazoa, Protista, Viridiplantae, Choanoflagellates, and Icththyosporeans. Among Bacteria, it is found in Kutzneria sp. 744, and an ornithine hydroxylase from Pseudomonas aeruginosa has a similar structure and 41% amino acid similarity to that of A. nidulans.
