Reaction: a 3β-hydroxysteroid-4α-carboxylate + NAD+ = a 3-oxosteroid + CO2 + NADH
Other name(s): 3β-HSD/D1 (gene name); 3β-HSD/D2 (gene name); 3β-hydroxysteroid dehydrogenases/C-4 decarboxylase (ambiguous)
Systematic name: 3β-hydroxysteroid-4α-carboxylate:NAD+ 3-oxidoreductase (decarboxylating)
Comments: The enzyme, found in plants, catalyses multiple reactions during plant sterol biosynthesis. Unlike the fungal/animal enzyme EC 126.96.36.199, 3β-hydroxysteroid-4α-carboxylate 3-dehydrogenase (decarboxylating), the plant enzyme is specific for NAD+.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Rondet, S., Taton, M. and Rahier, A. Identification, characterization, and partial purification of 4 α-carboxysterol-C3-dehydrogenase/ C4-decarboxylase from Zea mays. Arch. Biochem. Biophys. 366 (1999) 249-260. [PMID: 10356290]
2. Rahier, A., Darnet, S., Bouvier, F., Camara, B. and Bard, M. Molecular and enzymatic characterizations of novel bifunctional 3β-hydroxysteroid dehydrogenases/C-4 decarboxylases from Arabidopsis thaliana. J. Biol. Chem 281 (2006) 27264-27277. [PMID: 16835224]
3. Rahier, A., Bergdoll, M., Genot, G., Bouvier, F. and Camara, B. Homology modeling and site-directed mutagenesis reveal catalytic key amino acids of 3β-hydroxysteroid-dehydrogenase/C4-decarboxylase from Arabidopsis. Plant Physiol. 149 (2009) 1872-1886. [PMID: 19218365]