Proliferating Cell Nuclear Antigen (PCNA) is a cyclic trimer involved with a number of cellular processes. In general, PCNA works as a sliding ring-shaped clamp that anchors replisome proteins to double stranded DNA to prevent dissociation. In processive elongation of the leading and lagging strands of DNA, PCNA assembly is coupled with ATP hydrolysis by Replication Factor C (RFC) onto a primed DNA template.[1] PCNA then associates with DNA polymerase δ (pol δ) creating a holoenzyme so that pol δ synthesizes new DNA strands without dissociating from the DNA template. [2] Structural HighlightsThe PCNA monomers consist of 258 residues each and are a mass of 28.916 kDa. Each monomer contributes two domains to the trimeric ring. These domains possess anti-parallel beta sheets (blue) which approach each other on one end, but are separated by two alpha helices at the other (red), creating a 45 degree wedge in the sheets with alpha helices at the blunt end. The domains are connected by an extended beta sheet. This creates a six-fold symmetry within the trimeric ring and it also creates a β-α-β-β-β motif going around the ring. [3] Interaction with DNAThis is a sample scene created with SAT to color by Group, and another to make a transparent representation of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.
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This page was last modified 10:33, 11 October 2016.