Cryo-EM structure of the DNA-bound PolD–PCNA processive complex
Proliferating cell nuclear antigen (PCNA) is a DNA clamp that acts as a processivity factor for DNA polymerase δ in eukaryoticcells and is essential for replication. PCNA is a homotrimer and achieves its processivity by encircling the DNA, where it acts as a scaffold to recruit proteins involved in DNA replication, DNA repair, chromatin remodeling and epigenetics.[5]
Many proteins interact with PCNA via the two known PCNA-interacting motifs PCNA-interacting peptide (PIP) box[6] and AlkB homologue 2 PCNA interacting motif (APIM).[7] Proteins binding to PCNA via the PIP-box are mainly involved in DNA replication whereas proteins binding to PCNA via APIM are mainly important in the context of genotoxic stress.[8]