InterPro domain: IPR033942

This entry includes inositol monophosphatase (IMPase) and related proteins which are a family of Mg ⁺⁺ dependent phosphatases, inhibited by lithium, many of which may act on inositol monophosphate substrate. They dephosphorylate inositol phosphate to generate inositol, which may be recycled into inositol lipids; in eukaryotes IMPase plays a vital role in intracellular signaling [ 1 ]. IMPase is one of the proposed targets of Li ⁺ therapy in manic-depressive illness [ 2 , 3 ]. This family contains some bacterial members of the inositol monophosphatase family classified as SuhB-like. E. coli SuhB has been suggested to participate in posstranscriptional control of gene expression, and its inositol monophosphatase activity doesn't appear to be sufficient for its cellular function. It has been proposed, that SuhB plays a role in the biosynthesis of phosphatidylinositol in mycobacteria [ 4 ].

1. cDNA cloning of human and rat brain myo-inositol monophosphatase. Expression and characterization of the human recombinant enzyme. Biochem. J. 284 ( Pt 3), 749-54
2. Structure of inositol monophosphatase, the putative target of lithium therapy. Proc. Natl. Acad. Sci. U.S.A. 89, 10031-5
3. Molecular targets of lithium action. Annu. Rev. Pharmacol. Toxicol. 41, 789-813
4. Overexpression, purification, and analysis of complementation behavior of E. coli SuhB protein: comparison with bacterial and archaeal inositol monophosphatases. Biochemistry 39, 4145-53