Retinoblastoma-binding protein 8 (RBBP8), also known as CtIP, is an endonuclease that cooperates with the MRE11-RAD50-NBN (MRN) complex in processing meiotic and mitotic double-strand breaks (DSBs) by ensuring both resection and intrachromosomal association of the broken ends [, ]. CtIP interacts with the BRCA1 tumour suppressor []. BRCA1 and CtIP are required to recruit Dna2 at DSBs in homologous recombination, ensuring robust DSB resection []. CtIP it is not a tumuor suppressor itself, instead, it can promote tumourigenesis. This is probably related to its role in the formation of chromosomal rearrangements through the microhomology-mediated end joining (MMEJ) pathway, a relatively error-prone pathway of DSB repair [].
This entry includes DNA endonuclease RBBP8 from animals, Ctp1 from fission yeast and protein gamma response 1 from plants []. This entry also includes human RBBP8 N-terminal-like protein (RBBP8NL) whose function is not clear. RBBP8 is an endonuclease that cooperates with the MRE11-RAD50-NBN (MRN) complex in processing meiotic and mitotic double-strand breaks (DSBs) by ensuring both resection and intrachromosomal association of the broken ends []. Ctp1 is an endonuclease that cooperates with the MRN complex in processing meiotic and mitotic double-strand breaks by allowing the endonucleolytic removal of rec12 from the break sites and ensuring both resection and intrachromosomal association of the broken ends [].
This entry represents the C-terminal domain of the fission yeast Ctip (Ctp1) protein. Proteins containing this domain include DNA endonuclease RBBP8 (also known as CtBP-interacting protein, CtIP) from animals, protein gamma response 1 (GR1) from Arabidopsis and SAE2 from S. cerevisiae [, ]. SAE2 is a protein involved in repairing meiotic and mitotic double-strand breaks in DNA [, , ].Although proteins containing this domain were described as endonucleases, it is now known that they actually function as endonuclease activators that cooperates with the MRE11-RAD50-NBN (MRN) complex in processing meiotic and mitotic double-strand breaks (DSBs) by ensuring both resection and intrachromosomal association of the broken ends [, , ]. This domain contains highly conserved residues at its 15-residue extreme that are indispensable for MRN (Mre11-Rad50-Nbs1) complex activation, through the stimulation of Mre11 endonuclease activity [].
