Cell cycle checkpoint control protein RAD9A (RAD9A)

Component of the 9-1-1 cell-cycle checkpoint response complex that plays a significant role in DNA repair. The 9-1-1 complex is recruited to DNA lesion upon harm by the RAD17-replication factor C (RFC) clamp loader complex.

Acts then as a sliding clamp platform on DNA for many proteins involved in long-patch base excision repair (LP-BER). The 9-1-1 complex stimulates DNA polymerase beta (POLB) activity by increasing its affinity for the 3'-OH end of the primer-template and stabilizes POLB to those sites where LP-BER proceeds; endonuclease FEN1 cleavage activity on substrates with double, nick, or gap flaps of different sequences and lengths; and DNA ligase I (LIG1) on long-patch base excision repair substrates.