CPX1 (Coproporphyrinogen-III oxidase 1) is a key enzyme of heme biosynthesis. It is catalyzing the oxidative decarboxylation of propionic acid side chains of rings A and B of coproporphyrinogen III.Alternative name: Protein LESION INITIATION 2, AtCPO-I, Coprogen oxidase, Coproporphyrinogenase