Rad5 Background Information Considerable homology has recently been noted between the proteins encoded by the Rad5, Rad16 and Rad54 genes of Saccharomyces cerevisiae (1). These genes are members of the Rad6, Rad3 and Rad50 epistasis groups, respectively, which correspond to the three major DNA repair pathways in yeast (1-3). The Rad5 gene functions in postreplication repair of ultraviolet damaged DNA, and interestingly, it also has a role in increasing the instability of simple repetitive sequences in the genome (4-6). In contrast to DNA mismatch repair genes which function in maintaining constant length of repeat sequences, Rad5 promotes alterations in the length of repeat sequences (4).
