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 (By similarity). 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 (By similarity). Interacts with CDC6 and KAT7/HBO1 (By similarity). Interacts with LRWD1 predominantly during the G1 phase and with less affinity during mitosis, when phosphorylated (By similarity). The BAH domain mediates binding to dimethylated histone H4 'Lys-20' (H4K20me2), which is enriched at replication origins. Phosphorylated during mitosis. Belongs to the ORC1 family.