OXIDATION OF CYTOSOLIC NADH FORMED DURING AEROBIC METABOLISM IN MAMMALIAN-CELLS

In mammalian cells the sustained oxidation o f some important substrates depends on a continuous supply o f cytosolic NAD+. This is provided through the activity o f irreversible cyclic processes, or 'shuttle systems', which oxidize cytosolic NADH and transfer the reducing equivalents to the mitochondrial electron transport chain. Several different shuttle systems have been proposed and their operation varies according to the cell type and to the nature of the metabolic processes occurring therein. Metabolically versatile cells such as hepatocytes employ multiple shuttle systems simultaneously, whereas less versatile cells, such as tumour cells, often depend on a single shuttle system. © 1979.