Involved in the gluconeogenesis, in growth on fatty acids and is important for initiation of infection in the macrophages. Catalyzes the GTP-dependent conversion of oxaloacetate (OAA) to phosphoenolpyruvate (PEP), the rate-limiting step in the metabolic pathway that produces glucose from lactate and other precursors derived from the citric acid cycle. GTP + oxaloacetate = CO2 + GDP + phosphoenolpyruvate Binds 1 Mn(2+) ion per subunit. Carbohydrate biosynthesis; gluconeogenesis. Monomer. Belongs to the phosphoenolpyruvate carboxykinase [GTP] family.