Extrachromosomal Circular DNA are composed of chromatin and replicate in the nucleus of the cell during cell division. Unlike typical chromosomes, they are composed of circular fragments of DNA, up to only a few million base pairs in size and contain no centromere or telomere. Extrachromosomal Circular DNA Extrachromosomal circular DNA (eccDNA) is circular DNA found in the nuclei of plant and animal cells, including human cells, in addition to chromosomal DNA. eccDNA can be from 200 up to 5 million base pairs in length. eccDNA has been found in the nuclei of human cancer cells and shown to carry many copies of
DNA polymerase epsilon DNA polymerase epsilon DNA polymerase epsilon is a member of the DNA polymerase family of enzymes found in eukaryotes. It is composed of the following four subunits: POLE (central catalytic unit), POLE2 (subunit 2), POLE3 (subunit 3), and POLE4 (subunit 4). Recent evidence suggests that it plays a major role in leading strand DNA synthesis and nucleotide and base excision repair. Research had conducted to study nucleotide excision repair DNA synthesis by DNA polymerase epsilon in the presence of PCNA (proliferating cell nuclear antigen), RFC (replication factor C) and RPA (replication protein A). Either DNA polymerase epsilon or DNA polymerase