PCNA

Proliferating cell nuclear antigen (PCNA) plays a crucial role in nucleic acid metabolism as it pertains to DNA replication and repair.  Most noted for its activation of subunits of DNA polymerase, it has also been found to interact with cell-cycle progression proteins.  Modifications of PCNA as a result of cellular response put PCNA in a pivotal position with DNA replication, DNA damage, and chromatin structure and function.  In response to DNA damage, PCNA is ubiquitinated and becomes part of the RAD-6 dependent DNA repair pathway, where it acts as a substrate with a variety of p

Ki67, also known as MKI67, is best known as the leading marker of cellular proliferation. Ki67 is regulated by a balance between synthesis and degradation, and often carries a very short half-life.  First discovered to be located to dividing cells, Ki67 has since been specifically localized to the G1, S, G2 and M phases of mitosis. Soon after, it was discovered that there was a high correlation of Ki67 alongside the p53 (tumor suppressing protein 53), suggesting an implication in cancer. What’s more, the expression of Ki67 is higher in malignant cells versus control cells.

Caspase-3 is one of the most important players in apoptosis signaling. It is synthesized as an inactive 32 kDa pro-enzyme and upon direct activation by Caspase-8, -9 or -10, it gets processed into its active forms, the p17-20 and p10-12 subunits. The latter are responsible for the cleavage of PARP (poly ADP-ribose polymerase), actin and SREBP, which are associated with apoptosis [1].

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.

Proliferating cell nuclear antigen (PCNA) is an evolutionarily well-conserved protein found in all eukaryotic species as well as in Archaea. PCNA was first shown to be involved in DNA replication. However PCNA functions are associated with other vital cellular processes such as chromatin remodeling, DNA repair, sister-chromatid cohesion and cell cycle control as well (1).

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.