A V(D)J site-specific recombination model involving no compulsory double-stranded break formation at the coding segments.

Complete immunoglobulin and T-cell-receptor genes are assembled by site-specific recombination of separately encoded gene segments. We present a novel recombination model which accounts for all the characteristics of V(D)J recombination that have been described. The sequence of events proposed implies no formation of double-stranded breaks at the coding ends, ensuring continuity between the recombination partners during the reaction, and solves the problem of the ligation of extremities which have no complementarity. According to this recombination model, the formation of covalently sealed coding ends does not constitute a compulsory step in the recombination process.