A Drosophila Homolog of the Yeast Origin Recognition Complex

Abstract
Genes from Drosophila melanogaster have been identified that encode proteins homologous to Orc2p and Orc5p of the Saccharomyces cerevisiae origin recognition complex (ORC). The abundance of the Drosophila Orc2p homolog DmORC2 is developmentally regulated and is greatest during the earliest stages of embryogenesis, concomitant with the highest rate of DNA replication. Fractionation of embryo nuclear extracts revealed that DmORC2 is found in a tightly associated complex with five additional polypeptides, much like the yeast ORC. These studies will enable direct testing of the initiator-based model of replication in a metazoan.