PROSITE documentation PDOC00370

Hexokinases signature




Description

Hexokinase (EC 2.7.1.1) [1,2] is 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 designated glucokinase [3], is only expressed in liver and pancreatic β-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 (gene HXK1), PII (gene HXKB), and glucokinase (gene GLK1). 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 [4] to be involved in substrate binding. We have derived a pattern from that region.

Last update:

November 1997 / Pattern and text revised.

Technical section

PROSITE method (with tools and information) covered by this documentation:

HEXOKINASES, PS00378; Hexokinases signature  (PATTERN)


References

1AuthorsMiddleton R.J.
TitleHexokinases and glucokinases.
SourceBiochem. Soc. Trans. 18:180-183(1990).
PubMed ID2199258

2AuthorsGriffin L.D., Gelb B.D., Wheeler D.A., Davison D., Adams V., McCabe E.R.
TitleMammalian hexokinase 1: evolutionary conservation and structure to function analysis.
SourceGenomics 11:1014-1024(1991).
PubMed ID1783373

3AuthorsCornish-Bowden A., Luz Cardenas M.
SourceTrends Biochem. Sci. 16:281-282(1991).

4AuthorsSchirch D.M., Wilson J.E.
TitleRat brain hexokinase: location of the substrate hexose binding site in a structural domain at the C-terminus of the enzyme.
SourceArch. Biochem. Biophys. 254:385-396(1987).
PubMed ID3579310



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