InterPro domain: IPR000730

Proliferating cell nuclear antigen (PCNA), or cyclin, is a non-histone acidic nuclear protein [ 1 ] that plays a key role in the control of eukaryotic DNA replication [ 2 ]. It acts as a co-factor for DNA polymerase delta, which is responsible for leading strand DNAreplication [ 3 ]. 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 [ 4 ]. 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) [ 5 , 6 ] and in Paramecium bursaria Chlorella virus 1 (PBCV-1) and in nuclear polyhedrosis viruses.

1. Molecular cloning of cDNA coding for rat proliferating cell nuclear antigen (PCNA)/cyclin. EMBO J. 6, 637-42
2. Identification of carrot cDNA clones encoding a second putative proliferating cell-nuclear antigen, DNA polymerase delta auxiliary protein. Eur. J. Biochem. 203, 367-71
3. Structure of the human gene for the proliferating cell nuclear antigen. J. Biol. Chem. 264, 7466-72
4. Highly conserved structure of proliferating cell nuclear antigen (DNA polymerase delta auxiliary protein) gene in plants. Eur. J. Biochem. 195, 571-5
5. Functional interactions of a homolog of proliferating cell nuclear antigen with DNA polymerases in Archaea. J. Bacteriol. 181, 6591-9
6. Two DNA polymerase sliding clamps from the thermophilic archaeon Sulfolobus solfataricus. J. Mol. Biol. 291, 47-57