Origin recognition complex, subunit 1
InterPro Protein Domain record
-
description
-
-
<p> The Origin Recognition Complex (ORC) is a six-subunit ATP-dependent DNA-binding complex encoded in yeast by ORC1-6 [<cite idref="PUB00052559"/>]. ORC is a central component for eukaryotic DNA replication, and binds chromatin at replication origins throughout the cell cycle [<cite idref="PUB00052560"/>]. ORC directs DNA replication throughout the genome and is required for its initiation [<cite idref="PUB00052561"/>, <cite idref="PUB00052562"/>, <cite idref="PUB00052563"/>]. ORC bound at replication origins serves as the foundation for assembly of the pre-replicative complex (pre-RC), which includes Cdc6, Tah11 (aka Cdt1), and the Mcm2-7 complex [<cite idref="PUB00052564"/>, <cite idref="PUB00052565"/>, <cite idref="PUB00052566"/>]. Pre-RC assembly during G1 is required for replication licensing of chromosomes prior to DNA synthesis during S phase [<cite idref="PUB00052567"/>, <cite idref="PUB00052568"/>, <cite idref="PUB00052569"/>]. Cell cycle-regulated phosphorylation of Orc2, Orc6, Cdc6, and MCM by the cyclin-dependent protein kinase Cdc28 regulates initiation of DNA replication, including blocking reinitiation in G2/M phase [<cite idref="PUB00052560"/>, <cite idref="PUB00052570"/>, <cite idref="PUB00052571"/>, <cite idref="PUB00052572"/>]. </p><p> In yeast, ORC also plays a role in the establishment of silencing at the mating-type loci Hidden MAT Left (HML) and Hidden MAT Right (HMR) [<cite idref="PUB00052561"/>, <cite idref="PUB00052562"/>, <cite idref="PUB00052563"/>]. ORC participates in the assembly of transcriptionally silent chromatin at HML and HMR by recruiting the Sir1 silencing protein to the HML and HMR silencers [<cite idref="PUB00052563"/>, <cite idref="PUB00052573"/>, <cite idref="PUB00052574"/>]. </p><p> Both Orc1 and Orc5 bind ATP, though only Orc1 has ATPase activity [<cite idref="PUB00052575"/>]. The binding of ATP by Orc1 is required for ORC binding to DNA and is essential for cell viability [<cite idref="PUB00052566"/>]. The ATPase activity of Orc1 is involved in formation of the pre-RC [<cite idref="PUB00052576"/>, <cite idref="PUB00052577"/>, <cite idref="PUB00052578"/>]. ATP binding by Orc5 is crucial for the stability of ORC as a whole. Only the Orc1-5 subunits are required for origin binding; Orc6 is essential for maintenance of pre-RCs once formed [<cite idref="PUB00052579"/>]. Interactions within ORC suggest that Orc2-3-6 may form a core complex [<cite idref="PUB00052560"/>]. </p><p> ORC homologues have been found in various eukaryotes, including fission yeast, insects, amphibians, and humans [<cite idref="PUB00052580"/>]. </p><p> This entry represents the largest subunit of the origin recognition complex, subunit 1, which directs DNA replication by binding to replication origins and is also involved in transcriptional silencing; exhibits ATPase activity [<cite idref="PUB00052575"/>, <cite idref="PUB00011408"/>]. </p>
-
label
-
-
Origin recognition complex, subunit 1
-
attributionURL
-
-
signatures_SMART
-
-
type
-
-
seeAlso
-
-
children
-
-
contains
-
-
PDB_structure
-