PROSITE documentation PDOC00157
Glucose-6-phosphate isomerase (GPI) family signatures and profile


Glucose-6-phosphate isomerase (GPI) (EC 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 [3], 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 entire PGI.

Last update:

September 2009 / Text revised; profile added.


Technical section

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

P_GLUCOSE_ISOMERASE_3, PS51463; Glucose-6-phosphate isomerase family profile  (MATRIX)

P_GLUCOSE_ISOMERASE_1, PS00765; Phosphoglucose isomerase signature 1  (PATTERN)

P_GLUCOSE_ISOMERASE_2, PS00174; Phosphoglucose isomerase signature 2  (PATTERN)


1AuthorsAchari A. Marshall S.E. Muirhead H. Palmieri R.H. Noltmann E.A.
TitleGlucose-6-phosphate isomerase.
SourcePhilos. Trans. R. Soc. Lond., B, Biol. Sci. 293:145-157(1981).
PubMed ID6115414

2AuthorsSmith M.W. Doolittle R.F.
TitleAnomalous phylogeny involving the enzyme glucose-6-phosphate isomerase.
SourceJ. Mol. Evol. 34:544-545(1992).
PubMed ID1593646

3AuthorsFaik P. Walker J.I.H. Redmill A.A.M. Morgan M.J.
TitleMouse glucose-6-phosphate isomerase and neuroleukin have identical 3' sequences.
SourceNature 332:455-457(1988).
PubMed ID3352745

4AuthorsRead J. Pearce J. Li X. Muirhead H. Chirgwin J. Davies C.
TitleThe crystal structure of human phosphoglucose isomerase at 1.6 A resolution: implications for catalytic mechanism, cytokine activity and haemolytic anaemia.
SourceJ. Mol. Biol. 309:447-463(2001).
PubMed ID11371164

5AuthorsYamamoto H. Miwa H. Kunishima N.
TitleCrystal structure of glucose-6-phosphate isomerase from Thermus thermophilus HB8 showing a snapshot of active dimeric state.
SourceJ. Mol. Biol. 382:747-762(2008).
PubMed ID18675274

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