Cytosolic lactate dehydrogenase (LDH) catalyzes the freely reversible reaction of pyruvate (PYR) and NADH + H+ to form lactate (LACT) and NAD+. In liver parenchymal cells, this reaction allows lactate from red blood cells and exercising muscle to be converted to pyruvate which in turn is typically used for gluconeogenesis which also consumes the NADH from the reaction.
Lactate dehydrogenase is active as a tetramer. Two isoforms of lactate dehydrogenase, A and B, are widely expressed in human tissues, and all five tetramers - A4, A3B, A2B2, AB3, and B4 - are found (Read et al. 2001; Sakai et al. 1987; Yu et al. 2001). A third isoform, C, and its tetramer, C4, are found in testis (Millan et al. 1987; LeVan & Goldberg 1991). A fourth isoform, LDHAL6A, is less fully characterized than these others but limited data suggest that it may be testis-specific (Chen et al. 2009).
|Reverse Reaction||(S)-Lactate + NAD+ <=> Pyruvate + NADH + H+|
|LDH tetramer||L-lactate dehydrogenase activity (0004459)|
|18351441||Identification of a novel human lactate dehydrogenase gene LDHAL6A, which activates transcriptional activities of AP1(PMA)||Mol. Biol. Rep.||2009|
|1996957||Properties of human testis-specific lactate dehydrogenase expressed from Escherichia coli||Biochem. J.||1991|
|2440048||Epitopes of human testis-specific lactate dehydrogenase deduced from a cDNA sequence||Proc. Natl. Acad. Sci. U.S.A.||1987|
|11276087||Structural basis for altered activity of M- and H-isozyme forms of human lactate dehydrogenase||Proteins||2001|
|3435492||The cDNA and protein sequences of human lactate dehydrogenase B||Biochem J||1987|
|11377399||Selective active site inhibitors of human lactate dehydrogenases A4, B4, and C4||Biochem Pharmacol||2001|