Related Experiment Video
Updated: Aug 8, 2026

Induction and Assessment of Class Switch Recombination in Purified Murine B Cells
Published on: August 14, 2010
G4 DNA binding by LR1 and its subunits, nucleolin and hnRNP D, A role for G-G pairing in immunoglobulin switch
L A Dempsey1, H Sun, L A Hanakahi
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
Abstract:
The immunoglobulin heavy chain switch regions contain multiple runs of guanines on the top (nontemplate) DNA strand. Here we show that LR1, a B cell-specific, duplex DNA binding factor, binds tightly and specifically to synthetic oligonucleotides containing G-G base pairs (KD = 0.25 nM). LR1 also binds to single-stranded G-rich sequences (KD approximately 10 nM). The two subunits of LR1, nucleolin and hnRNP D, bind with high affinity to G4 DNA (KD = 0.4 and 0.5 nM, respectively). LR1 therefore contains two independent G4 DNA binding domains. We propose that LR1 binds with G-G-paired structures that form during the transcription of the S regions that is prerequisite to recombination in vivo. Interactions of donor and acceptor S regions with subunits of the LR1 could then juxtapose the switch regions for recombination.
Related Concept Videos
Homologous Recombination
Cooperative Binding of Transcription Regulators
Exon Recombination
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Cooperative Binding of Transcription Regulators
G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
Activation and Inactivation of G Proteins

