Maleylacetoacetate isomerase (EC # 5.2.1.2) catalyzes the fourth step of tyrosine degradation that leads to conversion of 4-maleyl-acetoacetate into fumaryl-acetoacetate. This protein has two enzymatic domains mapped to it, the other one is glutathione (EC # 2.5.1.18). This association was missing in the RiceCyc. We used Arabidopsis genes mapped to this reaction in the AraCyc and then identified rice orthologs from Gramene.