PCNA Recombinant Rabbit mAb (S-5313)

PCNA, or Proliferating Cell Nuclear Antigen, is a highly evolutionarily conserved homotrimeric ring-shaped protein composed of 261 amino acids with a molecular weight of approximately 29 kDa. Its three-dimensional structure presents as a closed circular "sliding clamp" with a central channel that can encircle and slide along double-stranded DNA. As a core component of the eukaryotic DNA replication machinery, PCNA serves as the processivity factor for DNA polymerases δ and ε during DNA replication, significantly enhancing their synthetic efficiency by anchoring the polymerases to the template strand. Simultaneously, it functions as a critical platform protein that bridges DNA replication, cell cycle regulation, and DNA damage repair networks. Through multiple protein interaction interfaces on its surface, PCNA can recruit and coordinate over dozens of different binding partners, including DNA ligase I, DNA methyltransferases, histone acetyltransferases, and the cyclin-dependent kinase (CDK) inhibitor p21. Notably, PCNA expression and synthesis peak during the S phase of the cell cycle, making it widely used as an immunohistochemical marker for cell proliferation status (e.g., as a complementary indicator to Ki-67). In response to DNA damage, specific lysine residues on PCNA undergo post-translational modifications such as ubiquitination and SUMOylation to switch its functional mode, shifting from supporting conventional replication to participating in DNA repair pathways such as translesion synthesis or template switching. Given that PCNA is highly expressed in actively proliferating tumor cells and is essential for cancer cell survival, inhibitors targeting PCNA—such as cyclic peptides or small-molecule compounds—are being actively developed as potential broad-spectrum anticancer agents.