FEN1

PCNA is a nuclear protein essential for DNA replication as well as DNA excision and mismatch repair pathways. It coordinates the recruitment and association of needed components during both of these processes, both of which are essential for cell cycle regulation and cell response to stress.  Through the symmetric association of three identical monomers, PCNA forms a toroidal, ring-shaped structure that encircles DNA. This serves as the scaffold upon which polymerases and other proteins dock and associate.

Proliferating Cell Nuclear Antigen (PCNA), also known as the polymerase delta auxiliary protein, is a nuclear protein essential for DNA replication as well as DNA excision and mismatch repair pathways. It has a large role in cell cycle regulation and response of cells to stress.

PCNA antibodies are useful biomarkers in DNA repair studies. PCNA is one of several proteins essential for the completion of nucleotide excision repair, a multi-stage process involving 20 - 30 proteins, and an important factor in repairing damage and mutations to the DNA helical structure.