The cyclin-like uracil DNA glycosylase (UDG) of murine oocytes and its relationship to human and chimpanzee homologues.

Examination of electrophoretically resolved randomly generated PCR amplicons from mature murine oocytes revealed the presence of a short sequence with partial homology to a cyclin-like human uracil DNA glycosylase (UDG2), a member of an important group of base-excision enzymes that remove misincorporated or cytosine-derived uracil from nascent DNA. A combination of 3' R.A.C.E. and in silico 'cloning' of the 5' region of the original EST uncovered a predicted murine mRNA sequence with limited homology to human UDG2 at both nucleotide and amino acid levels. An alternative contig for human UDG2 showed stronger similarity with the homologous murine and chimp genomic and protein sequences and contained both N and C terminal cyclin box elements. This contig is also an Ensembl annotated alternative splice-site variant of the UDG2 gene (Udg2v2). We suggest that uracil-excision repair in oocytes is likely to be mediated by Udg2v2, or alternatively that Udg2v2 is involved in a process related to oocyte-specific maturation by virtue of its cyclin-like domains.