May play an important role in maintaining the flux of carbon towards starch formation in endosperm. May also be involved in a sugar-sensing pathway. ATP + D-fructose = ADP + D-fructose 6-phosphate + H(+) Inhibited at high fructose. Glycan biosynthesis; starch biosynthesis. Expressed in stems, at higher levels in roots, and hardly detectable in leaves. Only detected at and after 15 days after pollination and remains at moderate level. Belongs to the carbohydrate kinase PfkB family.