{PDOC00157}
{PS00765; P_GLUCOSE_ISOMERASE_1}
{PS00174; P_GLUCOSE_ISOMERASE_2}
{PS51463; P_GLUCOSE_ISOMERASE_3}
{BEGIN}
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* Glucose-6-phosphate isomerase (GPI) family signatures and profile *
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Glucose-6-phosphate  isomerase  (GPI) (EC 5.3.1.9) 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 alpha-beta-alpha 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.

-Consensus pattern: [DENSA]-x-[LIVM]-[GP]-G-R-[FY]-[ST]-[LIVMFSTAP]-x-[GSTA]-
                    [PSTACM]-[LIVMSA]-[GSAN]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for PCC 6803 PGI.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Consensus pattern: [GSA]-x-[LIVMCAYQS]-[LIVMFYWN]-x(4)-[FY]-[DNTH]-Q-x-[GA]-
                    [IV]-[EQST]-x(2)-K
                    [K is the active site residue]

-Sequences known to belong to this class detected by the profile: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Last update: September 2009 / Text revised; profile added.

[ 1] Achari A., Marshall S.E., Muirhead H., Palmieri R.H., Noltmann E.A.
     "Glucose-6-phosphate isomerase."
     Philos. Trans. R. Soc. Lond., B, Biol. Sci. 293:145-157(1981).
     PubMed=6115414
[ 2] Smith M.W., Doolittle R.F.
     "Anomalous phylogeny involving the enzyme glucose-6-phosphate
     isomerase."
     J. Mol. Evol. 34:544-545(1992).
     PubMed=1593646
[ 3] Faik P., Walker J.I.H., Redmill A.A.M., Morgan M.J.
     "Mouse glucose-6-phosphate isomerase and neuroleukin have identical 3'
     sequences."
     Nature 332:455-457(1988).
     PubMed=3352745; DOI=10.1038/332455a0
[ 4] Read J., Pearce J., Li X., Muirhead H., Chirgwin J., Davies C.
     "The crystal structure of human phosphoglucose isomerase at 1.6 A
     resolution: implications for catalytic mechanism, cytokine activity
     and haemolytic anaemia."
     J. Mol. Biol. 309:447-463(2001).
     PubMed=11371164; DOI=10.1006/jmbi.2001.4680
[ 5] Yamamoto H., Miwa H., Kunishima N.
     "Crystal structure of glucose-6-phosphate isomerase from Thermus
     thermophilus HB8 showing a snapshot of active dimeric state."
     J. Mol. Biol. 382:747-762(2008).
     PubMed=18675274; DOI=10.1016/j.jmb.2008.07.041

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{END}