DEFINITION OF A CORE REGION OF RAG-2 THAT IS FUNCTIONAL IN V(D)J RECOMBINATION

The products of the RAG-1 and RAG-2 genes cooperate to allow V(D)J rec ombination in lymphoid and non-lymphoid cells. As one step toward unde rstanding the role of RAG-2, we have constructed mutated RAG-2 genes a nd examined their ability to support recombination of plasmid substrat es in a fibroblast cell line. The mutations define essential and dispe nsable parts of the RAG-2 gene. Mutations in the N-terminal part elimi nate almost all activity. In the central region of the protein, some b ut not all local alterations still allow recombination. On the other h and, proteins with large deletions from the C-terminal end, including one truncated by 25%, still retain activity, even though this part of the protein is highly conserved between species. Similar results were obtained with substrates that retain either a signal joint or a coding joint, or perform an inversion. Thus all basic features of V(D)J join ing are retained in a RAG-2 protein with only the first 75% of the seq uence.