GENETIC-EVIDENCE THAT THE RAG1 PROTEIN DIRECTLY PARTICIPATES IN V(D)JRECOMBINATION THROUGH SUBSTRATE RECOGNITION

RAG1 protein is essential for the activation of V(D)J recombination in developing lymphocytes (V, variable; D, diversity; J, joining). Howev er, it has not been determined whether its role involves substrate rec ognition and catalysis. A single amino acid substitution mutation in t he RAGI gene has now been. identified that renders its activity sensit ive to the sequence of the coding region abutting the heptamer site in the recombination signal sequence. These results strongly imply that RAG1 interacts directly with DNA.