A mammalian protein complex that repairs double-strand breaks and deletions by recombination.

摘要: We have purified a high molecular weight complex (RC-1) from calf thymus nuclei that catalyzes recombinational repair of double-strand gaps and deletions in DNA by gene conversion as well cross-over events leading to cointegrant products. These been detected polymerase chain reaction analysis using oligonucleotide primer pairs detect joined sequences originally present on only one or the other recombination substrates. RC-1 has an apparent mass about 550-600 kDa contains at least five polypeptide chains: masses 230, 210, 160, 130, 40 kDa. polymerase, identified epsilon, co-purifies with RC-1. A ligase, most likely mammalian ligase III, 5'-3' exonuclease also copurify Most preparations contain low levels endonuclease, 3'-5' single-strand nuclease activities. However, helicase, terminal deoxynucleotidyl transferase, topoisomerase I II were not The can act concert multiply gapped covalently repaired duplex. bovine single-strand-binding protein stimulates formation products mentioned above 4-fold.