LIG1 bound to APEX1 and PCNA ligates SSB

LIG1 (DNA ligase 1) is recruited to the long-patch base excision repair site through its interaction with APEX1, PCNA and RFC. LIG1 ligates the 3' end of the single strand break (SSB), containing the newly synthesized multiple nucleotide repair patch, with the FEN1-processed 5' end of the SSB, thus completing the base excision repair (Klungland and Lindahl 1997, Tomkinson et al. 2001, Ranalli et al. 2002a). The catalytic activity of LIG1 is stimulated by the presence of PCNA-bound RPA (Ranalli et al. 2002b)

LIG1（DNA连接酶1）通过与其相互作用，如APEX1、PCNA和RFC，被招募至长片段基团切除修复位点。LIG1能够连接单链断裂（SSB）的3'末端，其中包含新合成的多核苷酸修复区域，与SSB经过FEN1处理的5'末端，从而完成基团切除修复过程（Klungland and Lindahl 1997，Tomkinson et al. 2001，Ranalli et al. 2002a）。LIG1的催化活性在PCNA结合的RPA（Ranalli et al. 2002b）的存在下得到增强。