Component of the 9-1-1 cell-cycle checkpoint response complex that plays a major role in DNA repair. The 9-1-1 complex is recruited to DNA lesion upon damage by the RAD17-replication factor C (RFC) clamp loader complex. Acts then as a sliding clamp platform on DNA for several 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 distinct sequences and lengths; and DNA ligase I (LIG1) on long-patch base excision repair substrates.
Belongs to the HUS1 family.
Nucleus. Cytoplasm. In discrete nuclear foci upon DNA damage. According to PubMed:14500360, localized also in the cytoplasm. DNA damage induces its nuclear translocation. Shuttles between the nucleus and the cytoplasm.
Osorio-Zambrano WF & Davey S Chk1 Activation Protects Rad9A from Degradation as Part of a Positive Feedback Loop during Checkpoint Signalling. PLoS One10:e0144434 (2015).
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