Novel human and mouse homologs of Saccharomyces cerevisiae DNA polymerase eta

The Saccharomyces cerevisiae RAD30 gene encodes a novel eukaryotic DNA poly merase, poi eta that is able to replicate across cis-syn cyclobutane pyrimi dine dimers both accurately and efficiently. Very recently, a human homolog of RAD30 was identified, mutations in which result in the sunlight-sensiti ve, cancer-prone, Xeroderma pigmentosum variant group phenotype. We report here the cloning and localization of a second human homolog of RAD30. Inter estingly, RAD30B is localized on chromosome 18q21.1 in a region that is oft en implicated in the etiology of many human cancers. The mouse homolog (Rad 30b) is located on chromosome 18E2. The human RAD30B and mouse Rad30b mRNA transcripts, Like many repair proteins, are highly expressed in the testis. In situ hybridization analysis indicates that expression of mouse Rad30b o ccurs predominantly in postmeiotic round spermatids. Database searches reve aled genomic and EST sequences from other eukaryotes such as Aspergillus ni dulans, Schizosaccharomyces pombe, Brugia malayi, Caenorhabditis elegans, T rypanosoma cruzi, Arabidopsis thaliana and Drosophila melanogaster that als o encode putative homologs of RAD30, thereby suggesting that Rad30-dependen t translesion DNA synthesis is conserved within the eukaryotic kingdom. (C) 1999 Academic Press.