Fructose and glucose phosphorylating enzyme. May be involved in the phosphorylation of glucose during the export from plastids to cytosol. Seems neither to be involved in cell sugar sensing nor in carbohydrate metabolism in tuber. ATP + D-hexose = ADP + D-hexose 6-phosphate + H(+) ATP + D-fructose = ADP + D-fructose 6-phosphate + H(+) ATP + D-glucose = ADP + D-glucose 6-phosphate + H(+) Carbohydrate metabolism; hexose metabolism. Carbohydrate degradation; glycolysis; D-glyceraldehyde 3-phosphate and glycerone phosphate from D-glucose: step 1/4. Belongs to the hexokinase family.