Fig 1: CDC73 interacts with a number of chromatin-remodeling factors. (a) Co-IP with CDC73 confirmed its interaction with UBE1A, CAND1, CUL1, FBXO21, KU86, RUVBL2 and RNF20. PAF1 serves as a positive control and actin as a negative control. (b) The interactions are unchanged on IR treatment (2 Gy). (c) siRNA-mediated silencing of FBXO21, RUVBL2, CAND1, CUL1 and PAF1 leads to a decrease in H2BK120Ub. Ratios H2BK120Ub:H2B are indicated. (d) siRNA knockdown of CAND1, CUL1 and RUVBL2 leads to a similar decrease in homologous recombination repair as CDC73 knockdown (s.d. of average; more than three repeats). (e) Model describing the mode of action of CDC73 at DSB. CDC73 recruits chromatin-remodeling components that mediate H2BK120Ub and subsequent eviction of H2B from chromatin. The decondensed state of the chromatin allows repair enzymes to engage with DNA and proceed with resection and downstream DNA repair.