Initiation of V(D)J recombination in vitro obeying the 12/23 rule

Nature. 1996 Mar 7;380(6569):85-8. doi: 10.1038/380085a0.


V(D)J recombination, the process that assembles antigen-receptor genes, is directed by signal sequences flanking the DNA segments to be joined. Signals consist of a conserved heptamer and nonamer separated by a spacer of either 12 or 23 base pairs. Recombination occurs almost exclusively between two signals with spacers of different lengths. This restriction, called the '12/23 rule', governs the organization and pattern of rearrangement of antigen-receptor loci. In vitro work demonstrating the direct roles of the Rag proteins in the initiation of V(D)J recombination did not recreate the 12/23 rule. Instead, double-strand breaks were formed efficiently at isolated signals. Here we show that extracts made from a lymphoid cell line that expresses truncated forms of the Rag1 and Rag2 proteins have a signal-cutting activity that obeys the 12/23 rule. Cleavage at the two signals is concerted and requires their synapsis, and mutations of one signal prevent cleavage at both.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • Cell Line
  • DNA / genetics
  • DNA / metabolism*
  • DNA-Binding Proteins*
  • Homeodomain Proteins*
  • Molecular Sequence Data
  • Mutation
  • Proteins / genetics
  • Proteins / metabolism*
  • Receptors, Antigen / genetics*
  • Recombination, Genetic*
  • Regulatory Sequences, Nucleic Acid*
  • Transfection


  • DNA-Binding Proteins
  • Homeodomain Proteins
  • Proteins
  • Receptors, Antigen
  • V(D)J recombination activating protein 2
  • RAG-1 protein
  • DNA