|PROSITE documentation PDOC00370|
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 , 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  to be involved in substrate binding. We have derived a pattern from that region.Last update:
November 1997 / Pattern and text revised.
PROSITE method (with tools and information) covered by this documentation:
|Title||Hexokinases and glucokinases.|
|Source||Biochem. Soc. Trans. 18:180-183(1990).|
|2||Authors||Griffin L.D., Gelb B.D., Wheeler D.A., Davison D., Adams V., McCabe E.R.|
|Title||Mammalian hexokinase 1: evolutionary conservation and structure to function analysis.|
|3||Authors||Cornish-Bowden A., Luz Cardenas M.|
|Source||Trends Biochem. Sci. 16:281-282(1991).|
|4||Authors||Schirch D.M., Wilson J.E.|
|Title||Rat brain hexokinase: location of the substrate hexose binding site in a structural domain at the C-terminus of the enzyme.|
|Source||Arch. Biochem. Biophys. 254:385-396(1987).|