Protein Family Models

Members of this family include: purine nucleoside phosphorylase (PNP) Uridine phosphorylase (UdRPase) 5'-methylthioadenosine phosphorylase (MTA phosphorylase) [1]. 7920254. Unexpected sequence similarity between nucleosidases and phosphoribosyltransferases of different specificity. Mushegian AR, Koonin EV;. Protein Sci 1994;3:1081-1088. [2]. 9351810. The crystal structure of Escherichia coli purine nucleoside phosphorylase: a comparison with the human enzyme reveals a conserved topology. Mao C, Cook WJ, Zhou M, Koszalka GW, Krenitsky TA, Ealick SE;. Structure 1997;5:1373-1383. (from Pfam)

Date:

2024-10-16

purine-nucleoside phosphorylase catalyzes the phosphorolysis of purine nucleoside to form the corresponding free purine base and pentose-1-phosphate

Date:

2023-03-16

This model is a subset of the subfamily represented by PF00896 (phosphorylase family 2). This model excludes the methylthioadenosine phosphorylases (MTAP, TIGR01684) which are believed toplay a specific role in the recycling of methionine from methylthioadenosine. In this subfamily is found three clades of purine phosphorylases based on a neighbor-joining tree using the MTAP family as an outgroup. The highest-branching clade (TIGR01698) consists of a group of sequences from both gram positive and gram negative bacteria which have been annotated as purine nucleotide phosphorylases but have not been further characterized as to substrate specificity. Of the two remaining clades, one is xanthosine phosphorylase (XAPA, TIGR01699), is limited to certain gamma proteobacteria and constitutes a special purine phosphorylase found in a specialized operon for xanthosine catabolism. The enzyme also acts on the same purines (inosine and guanosine) as the other characterized members of this subfamily, but is only induced when xanthosine must be degraded. The remaining and largest clade consists of purine nucleotide phosphorylases (PNPH, TIGR01700) from metazoa and bacteria which act primarily on guanosine and inosine (and do not act on adenosine). Sequences from Clostridium (GP:15025051) and Thermotoga (OMNI:TM1596) fall between these last two clades and are uncharacterized with respect to substrate range and operon.

Date:

2024-05-30

This model represents a small clade of purine nucleotide phosphorylases found in certain gamma proteobacteria. The gene is part of an operon for the degradation of xanthosine and is induced by xanthosine [1]. The enzyme is also capable of acting on inosine and guanosine (but not adenosine) in a manner similar to those other phosphorylases to which it is closely related (TIGR01698, TIGR01700).

Gene:

xapA

Date:

2024-05-30

Catalyzes the formation of a purine and ribose phosphate from a purine nucleoside

Date:

2021-07-30