Malate dehydrogenases
malate dehydrogenases
Malate dehydrogenase (MDH) catalyzes the oxidation of L-malate to oxaloacetate in a reversible, NADH-dependent manner. MDH1 encodes a cytosolic protein that functions in multiple pathways, including the malate-aspartate shuttle and gluconeogenesis. MDH2 encodes a mitochondrial protein that catalyzes an essential step in the citric acid cycle. The main isoforms of MDH1 and MDH2 have been well characterized biochemically; both function as dimers. Domains for substrate binding, nucleotide binding, and dimer formation are highly conserved. MDH1B is predicted to have malate dehydrogenase activity but has not been tested to date. MDH1 and MDH2 are widely expressed, while MDH1B is only expressed in a small subset of tissues.