sentences:  In eukaryotes, the sliding clamp is a homotrimer ring structure known as the proliferating cell nuclear antigen (PCNA).The PCNA ring has polarity with surfaces that interact with DNA polymerases and tethers them securely to the DNA template.PCNA-dependent stabilization of DNA polymerases has a significant effect on DNA replication because PCNAs are able to enhance the polymerase processivity up to 1,000-fold.