TALDO is a reversible enzyme of the non-oxidative branch of the Pentose Phosphate Pathway (PPP).  The PPP plays a central role in generating ribose-5-phosphate for nucleic acid synthesis and NADPH for lipid biosynthesis.  This NADPH is used in the body’s biosynthetic reactions as well as in the maintenance of glutathione in a reduced state for protection against oxidative stress.  This pathway has both a reversible non-oxidative branch as well as an irreversible oxidative branch; both of which are inter-related.  The TALDO enzyme catalyzes the transfer of a three-carbon keto unit, corresponding to dihydroxyacetone (DHA), from sedoheptulose-7-phosphate (S7P) to glyceraldehyde-3-phosphate (G3P) generating erythrose-4-phosphate (E4P) and fructose-6-phosphate (F6P).

Deficiency of this enzyme leads to a condition characterized by hepatosplenomegaly, liver failure, and cutis laxa.  Individuals affected by this condition are also particularly susceptible to hepatocellular carcinoma, due to the resultant oxidative stress. 

The TALDO1 gene is located on the short arm of human chromosome 11 at 11p15.5, where it spans a length of about 17Kb.  The gene consists of eight exons, and its basal promoter activity is primarily mediated by the transcription factor ZNF143.  Additional positive regulatory elements have been found to map to the sequence -152 to +53, and negative regulatory regions to between -903 and -387.  The TALDO enzyme is made up of 337 amino acids, and contains an important alpha/beta barrel.  This barrel includes lysine 142, which is responsible for generating the Schiff base intermediate during sugar phosphate metabolism.  The protein is expressed in all cells, except the erythrocytes.