The enzyme from the bacterium Escherichia coli, which is specific for the (S)-enantiomer, is trifunctional, and also catalyses the reaction of EC
4.1.2.14, 2-dehydro-3-deoxy-phosphogluconate aldolase, and the beta-decarboxylation of oxaloacetate. cf. EC
4.1.3.16, 4-hydroxy-2-oxoglutarate aldolase.