Involved in the gluconeogenesis pathway. It converts oxaloacetic acid to phosphoenolpyruvate using ATP. Enzyme is a monomer. The reaction is also catalysed by phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) using GTP instead of ATP, described in PROSITE:PDOC00421 [Energy metabolism, Glycolysis/gluconeogenesis]