Threonine catabolism

In many mammals, threonine can be catabolized either via mitochondrial L-threonine 3-dehydrogenase (TDH) to yield acetyl-CoA and glycine or via cytosolic L-serine dehydratase/L-threonine deaminase (SDS and the related SDSL (SDS-like) protein) to yield 2-oxobutanoate. Data from rat liver suggests that usage of the two pathways varies with physiological state. Studies of healthy human subjects suggest that almost all threonine catabolism follows the 2-oxobutanoate pathway consistent with the finding that the human genomic TDH gene appears to encode a product that would be mis-spliced and catalytically inactive. Human threonine degradation is therefore annotated here as the conversion of threonine to 2-oxobutanoate and the related conversion of 2-iminobutanoate to 2-oxobutanoate.

Summary from Reactome (R-HSA-8849175), read 2026-09-23.