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Updated: Jul 7, 2026

Assessing Somatic Hypermutation in Ramos B Cells after Overexpression or Knockdown of Specific Genes
Published on: November 1, 2011
Cutting edge: a cis-acting DNA element targets AID-mediated sequence diversification to the chicken Ig light chain
Nagarama Kothapalli1, Darrell D Norton, Sebastian D Fugmann
1Molecular Immunology Unit, Laboratory of Cellular and Molecular Biology, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
Abstract:
Somatic hypermutation and gene conversion are two closely related processes that increase the diversity of the primary Ig repertoire. Both processes are initiated by the activation-induced cytidine deaminase that converts cytosine residues to uracils in a transcription-dependent manner; these lesions are subsequently fixed in the genome by direct replication and error-prone DNA repair. Two alternative mechanisms were proposed to explain why this mutagenic activity is targeted almost exclusively to Ig loci: 1) specific cis-acting DNA sequences; or 2) very high levels of Ig gene transcription. In this study we now identify a novel 3' regulatory region in the chicken Ig light chain gene containing not only a classical transcriptional enhancer but also cis-acting DNA elements essential for targeting activation-induced cytidine deaminase-mediated sequence diversification to this locus.
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