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Aliases ORC1, HSORC1L, PARC1, origin recognition complex subunit 1
External IDs MGI: 1328337 HomoloGene: 31221 GeneCards: 4998
RNA expression pattern
PBB GE ORC1L 205085 at tn.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr 1: 52.37 – 52.4 Mb Chr 4: 108.58 – 108.61 Mb
PubMed search [1] [2]
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Origin recognition complex subunit 1 is a protein that in humans is encoded by the ORC1 gene.[1][2]


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 the pre-replication complex, which includes additional initiation factors such as Cdc6 and Mcm proteins. The protein encoded by this gene is the largest subunit of the origin recognition 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.[2]


ORC1 has been shown to interact with:


  1. ^ Eki T, Okumura K, Amin A, Ishiai M, Abe M, Nogami M, Taguchi H, Hurwitz J, Murakami Y, Hanaoka F (Sep 1996). "Mapping of the human homologue (ORC1L) of the yeast origin recognition complex subunit 1 gene to chromosome band 1p32". Genomics 36 (3): 559–61. doi:10.1006/geno.1996.0511. PMID 8884289. 
  2. ^ a b "Entrez Gene: ORC1L origin recognition complex, subunit 1-like (yeast)". 
  3. ^ a b c d e f g h i j Kneissl M, Pütter V, Szalay AA, Grummt F (Mar 2003). "Interaction and assembly of murine pre-replicative complex proteins in yeast and mouse cells". Journal of Molecular Biology 327 (1): 111–28. doi:10.1016/s0022-2836(03)00079-2. PMID 12614612. 
  4. ^ Saha P, Chen J, Thome KC, Lawlis SJ, Hou ZH, Hendricks M, Parvin JD, Dutta A (May 1998). "Human CDC6/Cdc18 associates with Orc1 and cyclin-cdk and is selectively eliminated from the nucleus at the onset of S phase". Molecular and Cellular Biology 18 (5): 2758–67. doi:10.1128/mcb.18.5.2758. PMC 110655. PMID 9566895. 
  5. ^ a b c Méndez J, Zou-Yang XH, Kim SY, Hidaka M, Tansey WP, Stillman B (Mar 2002). "Human origin recognition complex large subunit is degraded by ubiquitin-mediated proteolysis after initiation of DNA replication". Molecular Cell 9 (3): 481–91. doi:10.1016/s1097-2765(02)00467-7. PMID 11931757. 
  6. ^ Iizuka M, Stillman B (Aug 1999). "Histone acetyltransferase HBO1 interacts with the ORC1 subunit of the human initiator protein". The Journal of Biological Chemistry 274 (33): 23027–34. doi:10.1074/jbc.274.33.23027. PMID 10438470. 
  7. ^ Fujita M, Ishimi Y, Nakamura H, Kiyono T, Tsurumi T (Mar 2002). "Nuclear organization of DNA replication initiation proteins in mammalian cells". The Journal of Biological Chemistry 277 (12): 10354–61. doi:10.1074/jbc.M111398200. PMID 11779870. 
  8. ^ Vashee S, Simancek P, Challberg MD, Kelly TJ (Jul 2001). "Assembly of the human origin recognition complex". The Journal of Biological Chemistry 276 (28): 26666–73. doi:10.1074/jbc.M102493200. PMID 11323433. 

Further reading[edit]