FEN1 bound to PCNA and APEX1 cleaves flap ssDNA

PCNA-bound FEN1 acts as a flap endonuclease to cleave the displaced single strand DNA (flap) containing the oxidatively damaged AP (apurinic/apyrimidinic) dideoxyribose residue (5'ddRP) that could not be excised by POLB. Interaction between FEN1 and PCNA or FEN1 and APE1 facilitate cleavage of flap structures (Klungland and Lindahl 1997, Matsumoto et al. 1999, Dianov et al. 1999).

PCNA 结合的 FEN1 蛋白作为一种 flap 端粒核酸酶，切割由氧化损伤的 AP（无嘌呤/无嘧啶）二脱氧核糖残基（5'-ddRP）组成的移位单链 DNA（flap），该残基无法被 POLB 剪切。FEN1 与 PCNA 或 FEN1 与 APE1 之间的相互作用有助于切开 flap 结构（Klungland 和 Lindahl 1997，Matsumoto 等人 1999，Dianov 等人 1999）。