DNAリガーゼ
Further research implicates the supplementary role of proliferating cell nuclear antigen (PCNA) to DNA ligase I's function of joining Okazaki fragments. When the PCNA binding site on DNA ligase I is inactive, DNA ligase I's ability to connect Okazaki fragments is severely impaired. Thus, a proposed mechanism follows: after a PCNA-DNA polymerase δ complex synthesizes Okazaki fragments, the DNA polymerase δ is released. Then, DNA ligase I binds to the PCNA, which is clamped to the nicks of the lagging strand, and catalyzes the formation of phosphodiester bonds.