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* Inositol monophosphatase family signatures *
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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 inositol monophosphatase (EC 3.1.3.25).
 - Vertebrate inositol polyphosphate 1-phosphatase (EC 3.1.3.57).

The function of the other proteins is not yet clear:

 - Escherichia coli protein cysQ. CysQ could  help  control  the  pool of PAPS
   (3'-phosphoadenoside 5'-phosphosulfate), or be useful in sulfite synthesis.
 - Escherichia coli protein suhB.  Mutations  in  suhB results in the enhanced
   synthesis of heat shock sigma factor (htpR).
 - 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.
 - A Rhizobium leguminosarum hypothetical protein encoded  upstream of the pss
   gene for exopolysaccharide synthesis.

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.

-Consensus pattern: W-x(0,1)-[LIVM]-D-P-[LIVM]-D-[SG]-T-x(2)-[FY]-x-[HKR]
                    [The first D and the T bind a metal ion]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Consensus pattern: W-D-x(2)-[GA](2)-x-[LIVMAN]-[LIVMA](2)-x(3)-[GA](2)
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in SWISS-PROT: NONE.

-Last update: October 1993 / Patterns and text revised.

[ 1] Neuwald A.F., York J.D., Majerus P.W.
     FEBS Lett. 294:16-18(1991).
[ 2] Glaeser H.-U., Thomas D., Gaxiola R., Montrichard F., Surdin-Kerjan Y.,
     Serrano R.
     EMBO J. 12:3105-3110(1993).
[ 3] Bone R., Springer J.P., Atack J.R.
     Proc. Natl. Acad. Sci. U.S.A. 89:10031-10035(1992).