PROSITE documentation PDOC00746 [for PROSITE entry PS00965]

Phosphomannose isomerase type I signatures


Phosphomannose isomerase (EC (PMI) [1,2] is the enzyme that catalyzes the interconversion of mannose-6-phosphate and fructose-6-phosphate. In eukaryotes, it is involved in the synthesis of GDP-mannose which is a constituent of N- and O-linked glycans as well as GPI anchors. In prokaryotes, it is involved in a variety of pathways including capsular polysaccharide biosynthesis and D-mannose metabolism.

Three classes of PMI have been defined on the basis of sequence similarities [1]. The first class comprises all known eukaryotic PMI as well as the enzyme encoded by the manA gene in enterobacteria such as Escherichia coli. Class I PMI's are proteins of about 42 to 50 Kd which bind a zinc ion essential for their activity.

As signature patterns for class I PMI, we selected two conserved regions. The first one is located in the N-terminal section of these proteins, the second in the C-terminal half. Both patterns contain a residue involved [3] in the binding of the zinc ion.

Expert(s) to contact by email:

Proudfoot A.E.I.

Last update:

November 1997 / Text revised.

Technical section

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

PMI_I_1, PS00965; Phosphomannose isomerase type I signature 1  (PATTERN)

PMI_I_2, PS00966; Phosphomannose isomerase type I signature 2  (PATTERN)


1AuthorsProudfoot A.E.I., Turcatti G., Wells T.N., Payton M.A., Smith D.J.
TitlePurification, cDNA cloning and heterologous expression of human phosphomannose isomerase.
SourceEur. J. Biochem. 219:415-423(1994).
PubMed ID8307007

2AuthorsCoulin F., Magnenat E., Proudfoot A.E.I., Payton M.A., Scully P., Wells T.N.C.
TitleIdentification of Cys-150 in the active site of phosphomannose isomerase from Candida albicans.
SourceBiochemistry 32:14139-14144(1993).
PubMed ID8260497

3AuthorsCleasby A., Wonacott A., Skarzynski T., Hubbard R.E., Davies G.J., Proudfoot A.E.I., Bernard A.R., Payton M.A., Wells T.N.C.
TitleThe x-ray crystal structure of phosphomannose isomerase from Candida albicans at 1.7 angstrom resolution.
SourceNat. Struct. Biol. 3:470-479(1996).
PubMed ID8612079

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