Phosphorylation of glucose
Glucose is converted to glucose-6-phosphate since phosphorylated intermediates do not readily penetrate cell membrane and this commits glucose to further metabolism in the cell. Hexokinase catalyses this irreversible reaction in most tissues and in liver; glucokinase is the predominant enzyme for the phosphorylation of glucose. Hexolcinase is an allosteric enzyme that is strongly inhibited by the product glucosed-phosphate.