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2  structures 537  species 0  interactions 628  sequences 18  architectures

Family: ORC2 (PF04084)

Summary: Origin recognition complex subunit 2

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This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Origin recognition complex subunit 2 Provide feedback

All DNA replication initiation is driven by a single conserved eukaryotic initiator complex termed he origin recognition complex (ORC). The ORC is a six protein complex. The function of ORC is reviewed in [1].

Literature references

  1. Bell SP; , Genes Dev 2002;16:659-672.: The origin recognition complex: from simple origins to complex functions. PUBMED:11914271 EPMC:11914271


This tab holds annotation information from the InterPro database.

InterPro entry IPR007220

The Origin Recognition Complex (ORC) is a six-subunit ATP-dependent DNA-binding complex encoded in yeast by ORC1-6 [PUBMED:17241905]. ORC is a central component for eukaryotic DNA replication, and binds chromatin at replication origins throughout the cell cycle [PUBMED:17825065]. ORC directs DNA replication throughout the genome and is required for its initiation [PUBMED:1579162, PUBMED:7585959, PUBMED:16716188]. 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 [PUBMED:7892251, PUBMED:7781615, PUBMED:16228006]. Pre-RC assembly during G1 is required for replication licensing of chromosomes prior to DNA synthesis during S phase [PUBMED:10966477, PUBMED:12045100, PUBMED:15680967]. 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 [PUBMED:17825065, PUBMED:11572976, PUBMED:11429609, PUBMED:16024805].

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) [PUBMED:1579162, PUBMED:7585959, PUBMED:16716188]. 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 [PUBMED:16716188, PUBMED:8622770, PUBMED:9171055].

Both ORC1 and ORC5 bind ATP, although only ORC1 has ATPase activity [PUBMED:9038340]. The binding of ATP by ORC1 is required for ORC binding to DNA and is essential for cell viability [PUBMED:16228006]. The ATPase activity of ORC1 is involved in formation of the pre-RC [PUBMED:11459976, PUBMED:15610739, PUBMED:16387651]. 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 [PUBMED:17053779]. Interactions within ORC suggest that ORC2-3-6 may form a core complex [PUBMED:17825065].

ORC homologues have been found in various eukaryotes, including fission yeast, insects, amphibians, and humans [PUBMED:9442876].

This entry represents subunit 2, which binds the origin of replication. It plays a role in chromosome replication and mating type transcriptional silencing.

Gene Ontology

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Domain organisation

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Alignments

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(142)
Full
(628)
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(1163)
NCBI
(1244)
Meta
(5)
RP15
(183)
RP35
(354)
RP55
(500)
RP75
(619)
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  Seed
(142)
Full
(628)
Representative proteomes UniProt
(1163)
NCBI
(1244)
Meta
(5)
RP15
(183)
RP35
(354)
RP55
(500)
RP75
(619)
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We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

  Seed
(142)
Full
(628)
Representative proteomes UniProt
(1163)
NCBI
(1244)
Meta
(5)
RP15
(183)
RP35
(354)
RP55
(500)
RP75
(619)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download   Download  
Gzipped Download   Download   Download   Download   Download   Download   Download   Download   Download  

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

HMM logo

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Trees

This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: Pfam-B_7065 (release 7.3);
Previous IDs: none
Type: Family
Author: Wood V, Finn RD
Number in seed: 142
Number in full: 628
Average length of the domain: 295.80 aa
Average identity of full alignment: 28 %
Average coverage of the sequence by the domain: 60.31 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 17690987 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 22.9 22.9
Trusted cut-off 22.9 22.9
Noise cut-off 22.7 22.8
Model length: 324
Family (HMM) version: 12
Download: download the raw HMM for this family

Species distribution

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Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the ORC2 domain has been found. There are 2 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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