Mammalian and human REC2

The present invention concerns the field of molecular genetics and medicine. Particularly, it concerns genes encoding a protein that is involved in homologous recombination and the repair of damaged genomic DNA in mammalian cells. Specifically the invention concerns the gene encoding a mammalian ATP-dependent homologous pairing protein; methods of using the gene to effect gene therapy; methods of using the gene and fragments of the gene to classify a mammalian tissue for medical purposes; and transgenic mice having had one or both alleles of the gene made inoperative. More specifically, the gene of the present invention is the human and murine homologs of the gene termed REC2 previously isolated from the fungus The invention concerns mammalian recombinase genes (REC2) and their promoters. Over expression of REC2 in a cell is found to facilitate homologous recombination, particularly homologous recombination using a DNA/RNA chimeric oligonucleotide and to sensitize a cell to the apoptotic effects of irradiation. The REC2 promoter, in combination with a strong enhancer, e.g., a SV40 enhancer, was found to be a strong promoter following irradiation of the cells. A radiation induceable promoter can be used to sensitize a cell to radiation treatment by operably linking the radiation induceable promoter to a gene whose expression converts a prodrug to a drug such as a herpes thymidien kinase gene.