PROSITE documentation PDOC00547
Inositol monophosphatase family signatures


It has been shown [1] that several proteins share two sequence motifs. Two of these proteins are enzymes of the inositol phosphate second messenger signalling pathway:

  • Vertebrate, plants and microbial myo-inositol monophosphatase (EC
  • Vertebrate inositol polyphosphate 1-phosphatase (EC

The function of the other proteins is not yet clear:

  • Bacterial protein cysQ. CysQ could help to control the pool of PAPS (3'-phosphoadenoside 5'-phosphosulfate), or be useful in sulfite synthesis.
  • Neurospora crassa protein Qa-X. Probably involved in quinate metabolism.
  • Emericella nidulans protein qutG. Probably involved in quinate metabolism.
  • Yeast protein HAL2/MET22 [2] involved in salt tolerance as well as methionine biosynthesis.
  • Yeast hypothetical hypothetical protein YHR046c.
  • Caenorhabditis elegans hypothetical protein F13G3.5.

It is suggested [1] that these proteins may act by enhancing the synthesis or degradation of phosphorylated messenger molecules. From the X-ray structure of human inositol monophosphatase [3], it seems that some of the conserved residues are involved in binding a metal ion and/or the phosphate group of the substrate.

Last update:

April 2006 / Pattern revised.


Technical section

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

IMP_1, PS00629; Inositol monophosphatase family signature 1  (PATTERN)

IMP_2, PS00630; Inositol monophosphatase family signature 2  (PATTERN)


1AuthorsNeuwald A.F. York J.D. Majerus P.W.
TitleDiverse proteins homologous to inositol monophosphatase.
SourceFEBS Lett. 294:16-18(1991).
PubMed ID1660408

2AuthorsGlaeser H.-U. Thomas D. Gaxiola R. Montrichard F. Surdin-Kerjan Y. Serrano R.
SourceEMBO J. 12:3105-3110(1993).

3AuthorsBone R. Springer J.P. Atack J.R.
TitleStructure of inositol monophosphatase, the putative target of lithium therapy.
SourceProc. Natl. Acad. Sci. U.S.A. 89:10031-10035(1992).
PubMed ID1332026

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