Asymmetric processing of coding ends and the effect of coding end nucleotide composition on V(D)J recombination.

The products of V(D)J recombination are coding and signal joints. We show that the nucleotide composition of the coding ends affects V(D)J recombination. The presence of Ts at the 5' end of either the 12 mer or the 23 mer recombination signal sequence (RSS) greatly decreases coding and signal joint formation, and Ts at the 5' ends of both RSSs eliminate recombination, suggesting that a step during the initiation phase of the recombination is affected. A 5' T coding end can be rescued it the other end contains 5' G, C, or A, implying that synapsis may be required. Furthermore, the presence of As at the 5' end of the 12 mer, but not the 23 mer, RSS affects coding but not signal joint formation. This observation of asymmetric processing of coding ends suggests that different protein complexes are bound to the two RSSs, and become transferred to the aligned coding ends during processing.