If antibody binds to normal tissues it can cause damage to the body or create other disease symptoms. Rheumatoid arthritis is a good example of an autoimmune disease. Antibodies that react with body tissues are felt to contribute to joint swelling and pain.
In eukaryotic cells the pyruvate decarboxylation occurs inside the mitochondria, after transport of the substrate, pyruvate, from the cytosol. The transport of pyruvate into the mitochondria is via a transport protein and is active, consuming energy. Passive diffusion of pyruvate into the mitochondria is impossible because it is a polar molecule. On entry to the mitochondria the pyruvate decarboxylation occurs, producing acetyl CoA.
In the absence of oxygen, the pyruvates are fermented into lactate, which recycles NADH into its oxidizing form, NAD+. If oxygen is present, the cell can reap much more energy through the oxidative decarboxylation of pyruvate and the citric acid cycle. Pyruvate at the Crossroads A cell can use the product of glycolysis, pyruvate, in several metabolic pathways besides decarboxylation.