D-glucose, D-mannose, D-fructose, sorbitol and D-glucosamine can act as acceptors. ITP and dATP can act as donors. The liver isoenzyme has sometimes been called glucokinase.

Hexokinaseis an important glycolytic enzyme that catalyzes the phosphorylation of keto- and aldohexoses (e.g. glucose, mannose and fructose) using MgATP as the phosphoryl donor.

In vertebrates there are four major isoenzymes, commonly referred as types I, II, III and IV. Type IV hexokinase, which is often incorrectly designate glucokinase, is only expressed in liver and pancreatic beta-cells and plays an important role in modulating insulin secretion; it is a protein of a molecular mass of about 50 Kd. Hexokinases of types I to III, which have low Km values for glucose, have a molecular mass of about 100 Kd. Structurally they consist of a very small N-terminal hydrophobic membrane-binding domain followed by two highly similar domains of 450 residues. The first domain has lost its catalytic activity and has evolved into a regulatory domain. In yeast there are three different isozymes: hexokinase PI, PII, and glucokinase. All three proteins have a molecular mass of about 50 Kd.

All these enzymes contain one (or two in the case of types I to III isozymes) strongly conserved region which has been shown to be involved in substrate binding. We have derived a pattern from that region.
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