Does phosphoenolpyruvate carboxykinase have a role in both amino acid and carbohydrate metabolism?

Phosphoenolpyruvate carboxykinase (PEPCK) catalyses the reversible decarbox ylation of oxaloacetate to yield phosphoenolpyruvate and CO2. The role of t he enzyme in gluconeogenesis and anaplerotic reactions in a range of organi sms is discussed, along with the important function in C-4 and CAM photosyn thesis in higher plants. In addition, new data are presented indicating tha t PEPCK may play a key role in amino acid metabolism. It is proposed that P EPCK is involved in the conversion of the carbon skeleton of asparagine/asp artate (oxaloacetate) to that of glutamate/glutamine (2-oxoglutarate). This metabolism is particularly important in the transport system, seeds and fr uits of higher plants.