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 cyclinlike human uracil DNA glycosylase (UDG2), a member of an important group of baseexcision enzymes that remove misincorporated or cytosinederived 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 splicesite variant of the UDG2 gene (Udg2v2). We suggest that uracilexcision repair in oocytes is likely to be mediated by Udg2v2, or alternatively that Udg2v2 is involved in a process related to oocytespecific maturation by virtue of its cyclinlike domains.