The enzyme represented by this model can convert crotonyl-CoA to butyryl-CoA (crotonyl-CoA reductase activity), but more importantly, in the presence of CO2, generates (2S)-ethylmalonyl-CoA. In serine cycle methylotrophic bacteria this enzyme is involved in the process of acetyl-CoA to glyoxylate. In other bacteria the enzyme is used to produce extender units for incorporation into polyketides such as tylosin from Streptomyces fradiae and coronatine from Pseudomonas syringae.
Jiyao W et al.(2023). "The conserved domain database in 2023.",