pubmed:abstractText |
V(D)J recombination is initiated by the introduction of double-stranded breaks (DSB) adjacent to recombination signal sequences (RSS). Each RSS contains a conserved heptamer and a conserved nonamer element separated by a 12 or 23 nucleotide spacer. In vivo, efficient recombination requires one RSS of each spacer length, although it has been unclear whether this '12/23 rule' regulates cleavage, joining, or both.
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