{PDOC00954}
{PS01240; PNP_MTAP_2}
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* Purine and other phosphorylases family 2 signature *
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The following phosphorylases belongs to the same family:

 - Purine  nucleoside phosphorylase (EC 2.4.2.1) (PNP) from mammals as well as
   from some  bacteria  (gene  deoD).  This  enzyme  catalyzes the cleavage of
   guanosine or  inosine  to  respective bases and sugar-1-phosphate molecules
   [1].
 - 5'-methylthioadenosine phosphorylase (EC 2.4.2.28) (MTA phosphorylase) from
   eukaryotes [2].
 - Xanthosine  phosphorylase  (EC  2.4.2.-) from Escherichia coli (gene xapA).
   This enzyme  can  degrade  all  purine  nucleosides  except  adenosine  and
   deoxyadenosine [3].

This family also includes the following uncharacterized proteins:

 - Yeast hypothetical protein YLR017w.
 - Fission yeast hypothetical protein SpAC16C9.02c.
 - Methanococcus jannaschii hypothetical protein MJ0060.
 - Rhodospirillum rubrum hypothetical protein in petC 3'region.

As a  signature pattern, we selected a conserved region in the central part of
these enzymes.

-Consensus pattern: [LIVF]-x(3)-[GS]-x(2)-H-x-[LIVMFY]-x(4)-[LIVMF]-x(3)-
                    [ATV]-x(1,2)-[LIVM]-x-[ATV]-x(4)-[GN]-x(3,4)-[LIVMF](2)-
                    x(2)-[STN]-[SAGT]-x-G-[GS]-[LIVM]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.

-Note: It  should  be noted that most bacterial PNP as well as archaebacterial
 MTA phosphorylase  belong  to  a  different  family  of  phosphorylases  (see
 <PDOC00946>).

-Last update: December 2004 / Pattern and text revised.

[ 1] Ealick S.E., Rule S.A., Carter D.C., Greenhough T.J., Babu Y.S.,
     Cook W.J., Habash J., Helliwell J.R., Stoeckler J.D., Parks R.E. Jr.
     Chen S.-F., Bugg C.E.
     "Three-dimensional structure of human erythrocytic purine nucleoside
     phosphorylase at 3.2 A resolution."
     J. Biol. Chem. 265:1812-1820(1990).
     PubMed=2104852
[ 2] Della Ragione F., Takabayashi K., Mastropietro S., Mercurio C.,
     Oliva A., Russo G.L., Della Pietra V., Borriello A., Nobori T.,
     Carson D.A., Zappia V.
     "Purification and characterization of recombinant human
     5'-methylthioadenosine phosphorylase: definite identification of
     coding cDNA."
     Biochem. Biophys. Res. Commun. 223:514-519(1996).
     PubMed=8687427
[ 3] Seeger C., Poulsen C., Dandanell G.
     "Identification and characterization of genes (xapA, xapB, and xapR)
     involved in xanthosine catabolism in Escherichia coli."
     J. Bacteriol. 177:5506-5516(1995).
     PubMed=7559336

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