PathwayStep2883 PathwayStep2879 PathwayStep2880 PathwayStep2881 PathwayStep2882 Resolution of AP sites via the single-nucleotide replacement pathway Authored: Matthews, L, 2004-02-09 03:00:00 Pubmed10583946 Reactome Database ID Release 43110381 Reactome, http://www.reactome.org ReactomeREACT_933 The single-nucleotide replacement pathway of base excision repair appears to facilitate the repair of most damaged bases. Following DNA glycosylase mediated cleavage of the damaged base, the endonuclease, APE1 is recruited to the site of damage where it cleaves the 5' side of the base-free deoxyribose residue. DNA polymerase, POL Beta then displaces the DNA glycosylase and cleaves the 3' side of the sugar phosphate. APE1 is subsequently released, the XRCC1:LIG3 complex is recruited and POL Beta mediates the synthesis of the replacement residue. Following LIG3 ligase mediated ligation of the replaced residue, the XRCC1:LIG3 complex dissociates (see Lindahl and Wood, 1999). An alternative BER pathway is employed when the structure of the terminal sugar phosphate is such that it can not be cleaved through the AP lyase activity of POL Beta. Base-free sugar-phosphate removal via the single-nucleotide replacement pathway Recruitment of LIG3:XRRC1 complex to the site of repair by POL Beta Dissociation of LIG3:XRCC1 complex from site of BER Resynthesis of excised residue DNA ligation via the single-nucleotide replacement pathway