Hexokinase, binding site

Definition

Hexokinase ([ec:2.7.1.1]) [[cite:PMID:2199258], [cite:PMID:1783373]] is an important glycolytic enzyme that catalyses 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 designated glucokinase PMID:1957348, 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 isoenzymes: hexokinase PI (gene HXK1), PII (gene HXKB), and glucokinase (gene GLK1). All three proteins have a molecular mass of about 50 Kd. The hexokinase domain has an α/β fold and is distinctly folded in two subdomains of unequal size: the large and small subdomains. The large subdomain comprises a six-stranded mixed β-sheet and a number of additional α-helices. On one side, the sheet packs against the small subdomain, and on the other side it is shielded by several α-helices. The dominant feature of the small subdomain is a five stranded mixed β-sheet. The sheet is flanked by two helices on one side and by one helix on the other. The subdomain also has an additional β-sheet formed by two antiparallel strands [[cite:PMID:10749890], [cite:PMID:9493266]]. 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 PMID:3579310. This entry represents the conserved region involved in substrate binding.

5 human proteins with this domain

Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.

Download CSV (5 proteins: gene, accession, name)

• GCK
• HK1
• HK2
• HK3
• HKDC1