Fructokinase that may play an important role in maintaining the flux of carbon towards starch formation. May also be involved in a sugar-sensing pathway. ATP + D-fructose = ADP + D-fructose 6-phosphate + H(+) Completely inhibited at 50 mM ATP, but not inhibited at high fructose concentration. Glycan biosynthesis; starch biosynthesis. Expressed in root, endosperm and leaf tissues. Belongs to the carbohydrate kinase PfkB family.