- Uroporphyrinogen decarboxylase in Saccharomyces cerevisiae. HEM12 gene sequence and evidence for two conserved glycines essential for enzymatic activity. Garey, J.R., Labbe-Bois, R., Chelstowska, A., Rytka, J., Harrison, L., Kushner, J., Labbe, P. Eur. J. Biochem. (1992)