Required for plastidial pyruvate kinase activity. Involved in seed oil accumulation, embryo development and seed storage compounds mobilization upon germination. ATP + pyruvate = ADP + H(+) + phosphoenolpyruvate Optimum pH is 7.8-8.0. Carbohydrate degradation; glycolysis; pyruvate from D-glyceraldehyde 3-phosphate: step 5/5. Oligomer of alpha and beta subunits. Mostly expressed in seeds, and, to a lower extent, in roots, leaves (veins and trichomes), inflorescences, siliques, pollen (grains and tubes) and flowers (sepals and petals). In seeds, accumulates in endosperm and embryo. In torpedo-shaped embryos, restricted to the hypocotyl and in the outer parts of the young cotyledons. In later embryo stages, present in all tissues except root tips. Reduced plastidial pyruvate kinase activity and altered seed oil content leading to wrinkled seeds, retarded embryo elongation and reduced seed germination. Belongs to the pyruvate kinase family.