Mannose-6-phosphate isomerase, type I (IPR001250)

Short name: Man6P_Isoase-1

Overlapping homologous superfamilies

Family relationships


Mannose-6-phosphate isomerase or phosphomannose isomerase (EC: (PMI) is the enzyme that catalyses the interconversion of mannose-6-phosphate and fructose-6-phosphate. In eukaryotes PMI is involved in the synthesis of GDP-mannose, a constituent of N- and O-linked glycans and GPI anchors and in prokaryotes it participates in a variety of pathways, including capsular polysaccharide biosynthesis and D-mannose metabolism. PMI's belong to the cupin superfamily whose functions range from isomerase and epimerase activities involved in the modification of cell wall carbohydrates in bacteria and plants, to non-enzymatic storage proteins in plant seeds, and transcription factors linked to congenital baldness in mammals [PMID: 11165500]. Three classes of PMI have been defined [PMID: 8307007].

Type I includes eukaryotic PMI and the enzyme encoded by the manA gene in enterobacteria. PMI has a bound zinc ion, which is essential for activity.

A crystal structure of PMI from Candida albicans shows that the enzyme has three distinct domains [PMID: 8612079]. The active site lies in the central domain, contains a single essential zinc atom, and forms a deep, open cavity of suitable dimensions to contain M6P or F6P The central domain is flanked by a helical domain on one side and a jelly-roll like domain on the other.

GO terms

Biological Process

GO:0005975 carbohydrate metabolic process

Molecular Function

GO:0004476 mannose-6-phosphate isomerase activity
GO:0008270 zinc ion binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.