ISOLATION OF HUMAN AND FISSION YEAST HOMOLOGS OF THE BUDDING YEAST ORIGIN RECOGNITION COMPLEX SUBUNIT ORC5 - HUMAN HOMOLOG (ORC5L) MAPS TO 7Q22

Orc5p is a subunit of the origin recognition complex in the budding ye ast Saccharomyces cerevisiae, which has been shown to play a critical role in both chromosomal DNA replication and transcriptional silencing . We have cloned cDNAs from both human and fission yeast Schizosacchar omyces pombe that encode pro teins homologous to the budding yeast and Drosophila Orc5p. Human Orc5p showed 35.1, 22.3, and 19.4% identity t o the Drosophila, S. pombe, and S. cerevisiae Orc5p, respectively. We have localized the human ORC5 gene (ORC5L) to chromosome 7 using South ern and PCR analysis of DNA isolated from a panel of human/rodent soma tic cell hybrids and mapped the gene locus to 7q22 using fluorescence in situ hybridization. We have identified a YAC clone that contains hu man ORC5L and maps to chromosome band 7q22.1. We have identified the S . pombe ORC5 gene and located it in a cosmid mapped on chromosome II. (C) 1997 Academic Press.