FIGURE 7.

Sequence characteristics of MTH3-related proteins. A, phylogenic tree of human Nudix family proteins. Structural alignment and the construction of a phylogenic tree were performed using the ClustalW program. NUDT1, NUDT15, and NUDT18 (characterized by their structural features) correspond to MTH1, MTH2, and MTH3, respectively, the names of which were assigned on the basis of their similar biochemical activities. B, comparison of the structures of the MutT family proteins. The numbers correspond to the positions of the amino acid residues from the N termini. The positions of the conserved MutT box are shown by shaded boxes. The relative numbers of amino acid residues identical to those of MTH3 are shown to the right of each sequence.