V(D)J Recombination: Links to Transposition and Double-strand Break Repair

The recombinational joining of gene segments to formthe functional immunoglobulin (Ig) and T-cell receptor(TCR) genes is an essential step in the development oflymphoid cells. This V(D)J recombination process is initiated by the action of the RAG1 and RAG2 proteins,which collaborate to cut DNA between the coding segments and the neighboring recombination signal sequences (RSSs). Such double-strand breaks (DSBs) havebeen observed in cells that are carrying out V(D)J recombination, and the reaction can be reproduced with the purified RAG proteins. The later stages of recombinationjoin pairs of RSSs and coding ends to produce precise signal joints and imprecise coding joints (for reviews, seeLewis 1994; Gellert 1997). In this paper, we summarizesome recent developments in understanding both theearly and late stages of V(D)J recombination...