Cell cycle regulator of non-homologous end joining (Cyren)

Cell-cycle-specific inhibitor of classical non- homologous end joining (NHEJ) of DNA double-strand break (DSB) repair during the S and G2 phases. Acts as a regulator of DNA repair pathway choice by specifically inhibiting classical NHEJ during the S and G2 phases, thereby promoting error-free repair by homologous recombination during cell cycle stages when sister chromatids are present.

Preferentially protects single-stranded overhangs at break sites by inhibiting classical NHEJ, thereby creating a local environment which favors homologous recombination. Acts via interaction with XRCC5/Ku80 and XRCC6/Ku70, interaction confined during the S and G2 phases only.