Glucose-6-phosphate isomerase (GPI) (EC 126.96.36.199) or phosphoglucose isomerase
(PGI) [1,2] is a dimeric enzyme that catalyzes the reversible isomerization of
glucose-6-phosphate and fructose-6-phosphate. PGI is involved in different
pathways: in most higher organisms it is involved in glycolysis; in mammals it
is involved in gluconeogenesis; in plants in carbohydrate biosynthesis; in
some bacteria it provides a gateway for fructose into the Entner-Doudouroff
pathway. Besides it's role as a glycolytic enzyme, mammalian PGI can function
as a tumor-secreted cytokine and an angiogenic factor (AMF) that stimulates
endothelial cell motility. Mammalian PGI is also neuroleukin , a
neurotrophic factor which supports the survival of various types of neurons.
The sequence of PGI is conserved among diverse species ranging from bacteria
to mammals and structures form a similar fold (see <PDB:1IAT>) [4,5],
comprised of two subdomains that each form an α-β-α sandwich, with
the active site located in the cleft between the subdomains and on the dimer
interface. A glutamate and a lysine residue as well as a histidine from the
other protomer in the dimer are implicated in the catalytic mechanism. The
structure resembles that of the SIS domain (see <PDOC51464>).
As signature patterns for this enzyme we selected two conserved regions, the
first region is located in the central section of PGI, while the second one is
located in its C-terminal section. We also developed a profile that covers the
September 2009 / Text revised; profile added.
PROSITE methods (with tools and information) covered by this documentation:
Achari A. Marshall S.E. Muirhead H. Palmieri R.H. Noltmann E.A.
Philos. Trans. R. Soc. Lond., B, Biol. Sci. 293:145-157(1981).
PROSITE is copyright. It is produced by the SIB Swiss Institute
Bioinformatics. There are no restrictions on its use by non-profit
institutions as long as its content is in no way modified. Usage by and
for commercial entities requires a license agreement. For information
about the licensing scheme send an email to
or see: prosite_license.html.