The origin recognition complex (ORC) is a highly conserved six subunits protein complex essential for the initiation of the DNA replication in eukaryotic cells. Studies in yeast demonstrated that ORC binds specifically to origins of replication and serves as a platform for the assembly of additional initiation factors such as Cdc6 and Mcm proteins. The protein encoded by this gene is the largest subunit of the ORC complex. While other ORC subunits are stable throughout the cell cycle, the levels of this protein vary during the cell cycle, which has been shown to be controlled by ubiquitin-mediated proteolysis after initiation of DNA replication. This protein is found to be selectively phosphorylated during mitosis. It is also reported to interact with MYST histone acetyltransferase 2 (MyST2/HBO1), a protein involved in control of transcription silencing. Alternatively spliced transcript variants encoding different isoforms have been found for this gene.ORC1 (Origin Recognition Complex Subunit 1) is a Protein Coding gene. Diseases associated with ORC1 include Meier-Gorlin Syndrome 1 and Microtia. Among its related pathways are E2F mediated regulation of DNA replication and CDK-mediated phosphorylation and removal of Cdc6. GO annotations related to this gene include chromatin binding. An important paralog of this gene is CDC6.