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Updated: May 17, 2026

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae
Published on: September 11, 2022
Localized epigenetic changes induced by DH recombination restricts recombinase to DJH junctions
Ramesh Subrahmanyam1, Hansen Du, Irina Ivanova
1Laboratory of Molecular Biology and Immunology, National Institute on Aging, US National Institutes of Health, Baltimore, Maryland, USA.
None:
Genes encoding immunoglobulin heavy chains (Igh) are assembled by rearrangement of variable (V(H)), diversity (D(H)) and joining (J(H)) gene segments. Three critical constraints govern V(H) recombination. These include timing (V(H) recombination follows D(H) recombination), precision (V(H) gene segments recombine only to DJ(H) junctions) and allele specificity (V(H) recombination is restricted to DJ(H)-recombined alleles). Here we provide a model for these universal features of V(H) recombination. Analyses of DJ(H)-recombined alleles showed that DJ(H) junctions were selectively epigenetically marked, became nuclease sensitive and bound RAG recombinase proteins, which thereby permitted D(H)-associated recombination signal sequences to initiate the second step of Igh gene assembly. We propose that V(H) recombination is precise, because these changes did not extend to germline D(H) segments located 5' of the DJ(H) junction.
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