Involved in microhomology-mediated end-joining (MMEJ) DNA repair by promoting recruitment of polymerase theta (POLQ) to DNA damage sites during mitosis . MMEJ is an alternative non-homologous end-joining (NHEJ) machinery that takes place during mitosis to repair double-strand breaks in DNA that originate in S-phase . Accumulates in M-phase; following phosphorylation by PLK1, interacts with POLQ, enabling its recruitment to double-strand breaks for subsequent repair . Also involved in the DNA damage response (DDR) signaling in response to genotoxic stresses such as ionizing radiation (IR) during the S phase (, ). Recruited to sites of DNA damage through interaction with the 9-1-1 cell-cycle checkpoint response complex and TOPBP1 in a ATR-dependent manner (, ). Required for the progression of the G1 to S phase transition . Plays a role in the stimulation of CHEK1 phosphorylation .
Subcellular locations: Nucleus, Chromosome
Localizes to sites of DNA damage in a H2AX-independent manner.
Weakly expressed in testis, prostate, ovary, thymus and small intestine . Expressed strongly in breast cancer cells .