Catalyzes the 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. Monomer. Belongs to the phosphoenolpyruvate carboxykinase [GTP] family. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.