InterPro domain: IPR006434

This family is a small group of metazoan sequences with sequences from Arabidopsis thaliana (Mouse-ear cress) and rice. The sequences represent pyrimidine 5-nucleotidases, apparently in reference to HSPC233, the Homo sapiens (Human) homologue [ 1 ]. The structure of mouse sequence has been reported [ 2 ]. This group of sequences was originally found during searches for members of the haloacid dehalogenase (HAD) superfamily. All of the conserved catalytic motifs [ 3 ] are found. The placement of the variable domain between motifs 1 and 2 indicates membership in subfamily I of the superfamily, but these sequences are sufficiently different from any of the branches of that subfamily (IA-ID) as to constitute a separate branch to now be called IE. Considering that the closest identifiable hit outside of the noise range is to a phosphoserine phosphatase, this group may be considered to be most closely allied to subfamily IB.

1. Human erythrocyte pyrimidine 5-nucleotidase, PN-I, is identical to p36, a protein associated to lupus inclusion formation in response to alpha-interferon. Blood 96, 1596-8
2. Structure of pyrimidine 5'-nucleotidase type 1. Insight into mechanism of action and inhibition during lead poisoning. J. Biol. Chem. 281, 20521-9
3. Computer analysis of bacterial haloacid dehalogenases defines a large superfamily of hydrolases with diverse specificity. Application of an iterative approach to database search. J. Mol. Biol. 244, 125-32