InterPro domain: IPR035482

Phosphoglucose isomerase (PGI) is a multifunctional enzyme which as an intracellular dimer catalyzes the reversible isomerization of glucose 6-phosphate to fructose 6-phosphate [ 1 ]. As an extracellular protein, PGI also has functions equivalent to neuroleukin (NLK), autocrine motility factor (AMF), and maturation factor (MF) [ 2 , 3 ]. Evidence suggests that PGI, NLK, AMF, and MF are closely related or identical. NLK is a neurotrophic growth factor that promotes regeneration and survival of neurons. The dimeric form of NLK has isomerase function, whereas its monomeric form carries out neurotrophic activity. AMF is a cytokine that stimulates cell migration and metastasis. MF mediates the differentiation of human myeloid leukemic HL-60 cells to terminal monocytic cells.

PGI is comprised of two domains; each domain is an alpha-beta-alpha sandwich [ 4 ], which correspond to a SIS (Sugar ISomerase) domain fold.

1. Glucose-6-phosphate isomerase. Philos. Trans. R. Soc. Lond., B, Biol. Sci. 293, 145-57
2. The crystal structure of a multifunctional protein: phosphoglucose isomerase/autocrine motility factor/neuroleukin. Proc. Natl. Acad. Sci. U.S.A. 96, 5412-7
3. The crystal structure of phosphoglucose isomerase/autocrine motility factor/neuroleukin complexed with its carbohydrate phosphate inhibitors suggests its substrate/receptor recognition. J. Biol. Chem. 275, 23154-60
4. 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, 447-63