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391  structures 1800  species 0  interactions 2638  sequences 49  architectures

Family: PCNA_C (PF02747)

Summary: Proliferating cell nuclear antigen, C-terminal domain

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Proliferating cell nuclear antigen, C-terminal domain Provide feedback

N-terminal and C-terminal domains of PCNA are topologically identical. Three PCNA molecules are tightly associated to form a closed ring encircling duplex DNA.

Literature references

  1. Krishna TS, Kong XP, Gary S, Burgers PM, Kuriyan J; , Cell 1994;79:1233-1243.: Crystal structure of the eukaryotic DNA polymerase processivity factor PCNA. PUBMED:8001157 EPMC:8001157

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR022649

Proliferating cell nuclear antigen (PCNA), or cyclin, is a non-histone acidic nuclear protein [ PUBMED:2884104 ] that plays a key role in the control of eukaryotic DNA replication [ PUBMED:1346518 ]. It acts as a co-factor for DNA polymerase delta, which is responsible for leading strand DNA replication [ PUBMED:2565339 ]. The sequence of PCNA is well conserved between plants and animals, indicating a strong selective pressure for structure conservation, and suggesting that this type of DNA replication mechanism is conserved throughout eukaryotes [ PUBMED:1671766 ]. In Saccharomyces cerevisiae (Baker's yeast), POL30, is associated with polymerase III, the yeast analog of polymerase delta.

Homologues of PCNA have also been identified in the archaea (known as DNA polymerase sliding clamp) [ PUBMED:10542158 , PUBMED:10438605 ] and in Paramecium bursaria Chlorella virus 1 (PBCV-1) and in nuclear polyhedrosis viruses.

The N-terminal and C-terminal domains of PCNA are topologically identical. Three PCNA molecules are tightly associated to form a closed ring encircling duplex DNA [ PUBMED:8001157 ].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan DNA_clamp (CL0060), which has the following description:

Sliding DNA clamps are ring-shaped proteins that allow DNA polymerase to achieve high processivity during chromosome replication by tethering the polymerase catalytic subunit to DNA. All of the structures share a 12-fold symmetry around the ring consisting of a simple structural repeat, though there is structural divergence in some of the repeats. Bacterial beta-clamps contain six repeats per subunit with two subunits per ring while the eukaryotic and bacteriophage clamps contain four repeats per subunit with three subunits per ring. Pairs of these repeats form a domain, which has been termed the 'processivity fold'; thus the ring of the sliding clamp contains six domains and therefore is often described as having 6-fold symmetry. A structural representative of a fourth family of processivity fold proteins, namely the herpes simplex virus UL42 protein, is also available. UL42 does not form a ring-shaped clamp, however, but rather functions as a monomer and interacts with DNA quite differently than do sliding clamps; it has been suggested that UL42 resembles a primitive ancestor of sliding clamps [2].

The clan contains the following 13 members:

DNA_pol3_beta DNA_pol3_beta_2 DNA_pol3_beta_3 DNA_PPF gp45-slide_C Herpes_DNAp_acc Herpes_PAP Herpes_UL42 Hus1 PCNA_C PCNA_N Rad1 Rad9


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Representative proteomes UniProt

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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_598 (release 2.1)
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Bateman A , Griffiths-Jones SR
Number in seed: 6
Number in full: 2638
Average length of the domain: 115.90 aa
Average identity of full alignment: 38 %
Average coverage of the sequence by the domain: 41.55 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 23.0 23.0
Trusted cut-off 23.0 23.0
Noise cut-off 22.9 22.9
Model length: 128
Family (HMM) version: 18
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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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 PCNA_C domain has been found. There are 391 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 sequence.

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