FUNCTION Component of the origin recognition complex (ORC) that binds origins of replication. DNA-binding is ATP-dependent. The specific DNA sequences that define origins of replication have not been identified yet. ORC is required to assemble the pre-replication complex necessary to initiate DNA replication. Binds histone H3 and H4 trimethylation marks H3K9me3, H3K27me3 and H4K20me3.SUBUNIT Component of ORC, a complex composed of at least 6 subunits: ORC1, ORC2, ORC3, ORC4, ORC5 and ORC6. ORC is regulated in a cell-cycle dependent manner. It is sequentially assembled at the exit from anaphase of mitosis and disassembled as cells enter S phase (PubMed:12909626, PubMed:17716973). Interacts with DBF4 (By similarity). Interacts with POLQ (PubMed:24989122).INTERACTION The disease is caused by variants affecting the gene represented in this entry.SIMILARITY Belongs to the ORC4 family.