cd00577: PCNA (This model is not part of the current CDD release)
Proliferating Cell Nuclear Antigen
Proliferating Cell Nuclear Antigen (PCNA), also called DNA polymerase sliding clamp, is a multitasking protein that forms a homotrimeric ring that encircles the DNA. It plays a significant role in all three major challenges of replication: faithfully replicating DNA even in the presence of DNA damage, preserving and duplicating chromatin structure, and establishing sister chromatid cohesion. It serves as a processivity factor for DNA polymerases and acts as a landing platform for different proteins interacting with DNA and chromatin. PCNA encircles duplex DNA in its central cavity, providing a DNA-bound platform for the attachment of the polymerase. The trimeric PCNA ring is structurally similar to the dimeric ring formed by the DNA polymerase processivity factors in bacteria (beta subunit DNA polymerase III holoenzyme) and in bacteriophages (catalytic subunits in T4 and RB69). This structural correspondence substantiates the mechanistic connection between eukaryotic and prokaryotic DNA replication. PCNA is also involved with proteins involved in cell cycle processes such as DNA repair and apoptosis. Many of these proteins contain a highly conserved motif known as the PIP-box (PCNA interacting protein box) which contains the sequence Qxx[LIM]xxF[FY].
Jiyao W et al.(2023). "The conserved domain database in 2023.",