{PDOC00325}
{PS00387; PPASE}
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* Inorganic pyrophosphatase signature *
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Inorganic pyrophosphatase (EC 3.6.1.1) (PPase) [1,2] is the enzyme responsible
for the hydrolysis of pyrophosphate (PPi) which  is  formed principally as the
product of the many biosynthetic reactions that utilize ATP.  All known PPases
require the presence of divalent metal cations, with magnesium  conferring the
highest activity.  Among other residues, a  lysine has  been  postulated to be
part or  close  to  the active site.  PPases have been sequenced from bacteria
such as Escherichia coli (homohexamer), thermophilic bacteria PS-3 and Thermus
thermophilus, from  the archaebacteria  Thermoplasma  acidophilum, from  fungi
(homodimer), from a plant, and from bovine retina.  In  yeast, a mitochondrial
isoform of PPase  has been characterized which  seems to be involved in energy
production and whose activity is stimulated by uncouplers of ATP synthesis.

The sequences  of PPases share  some  regions of  similarities.  As  signature
patterns we have selected a  region  that  contains three conserved aspartates
that are involved in the binding of cations.

-Consensus pattern: D-[SGDN]-D-[PE]-[LIVMF]-D-[LIVMGAC]
                    [The 3 D's bind divalent metal cations]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: 24.

-Expert(s) to contact by email:
           Kolakowski L.F. Jr.; kolakowski@uthsca.edu

-Last update: May 2004 / Text revised.

[ 1] Lahti R., Kolakowski L.F. Jr., Heinonen J., Vihinen M., Pohjanoksa K.,
     Cooperman B.S.
     "Conservation of functional residues between yeast and E. coli
     inorganic pyrophosphatases."
     Biochim. Biophys. Acta 1038:338-345(1990).
     PubMed=2160278
[ 2] Cooperman B.S., Baykov A.A., Lahti R.
     "Evolutionary conservation of the active site of soluble inorganic
     pyrophosphatase."
     Trends Biochem. Sci. 17:262-266(1992).
     PubMed=1323891

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