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Nuclear protein binding to octamer motifs in the immunoglobulin γ1 switch region

Nuclear protein binding to octamer motifs in the immunoglobulin γ1 switch region Abstract Initiation of the Immunoglobulin heavy chain switch DNA rearrangement event is thought to involve conversion of the target switch region DNA to an accessible state. Accessibility is likely to be mediated by the binding of regulatory proteinsto sequences in or near switch regions. A DNase hypersensitlvity assay was used to recognize possible regions of protein binding in the γ1 switch region of the B cell hybridoma 470.25. A strong DNase hypersensitive site was identified 5'of the tandemly repeated Sγ1 sequences. Data from other laboratories suggest that this hypersensitive siteis associated with switch recombination to γ1 However, the 470.25 cell does not express the γ1 germllne transcript. A second group of DNase hypersensitive sites within the repetitive portion of the γ1 switch region was alsoidentified. A gel retardation assay for protein - DNA interaction revealed a sequence present in several copies in the γ1 switch region that specifically binds nuclear proteins. This binding sequence, SG1BS, contains the octanucleotide sequence ATGCAAAA, a 7/8 match to the transcrlptlonal enhancer octamer motif found in immunoglobulin promoters and the heavy chain enhancer. Binding competition studies of SG1BS demonstrate that both the octamer and flanking sequences are critical for binding. By size- and tissue-distribution, the factors that bind SG1BS are not distinguishable from the previously identified octamer-binding factors OTF-1 and OTF-2. The ability of proteins to bind the Sγ1 octamer motifis increased 2.3-fold upon IL-4 induction of lipopolysaccharide-stlmulated B cells. DNase-hypersensitive sites, sterile transcripts, chromatin accessibility This content is only available as a PDF. Author notes 1Present address: DNAX Research Institute, Palo Alto, CA 94304, USA © Oxford University Press http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Immunology Oxford University Press

Nuclear protein binding to octamer motifs in the immunoglobulin γ1 switch region

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Publisher
Oxford University Press
Copyright
© Oxford University Press
ISSN
0953-8178
eISSN
1460-2377
DOI
10.1093/intimm/3.2.109
Publisher site
See Article on Publisher Site

Abstract

Abstract Initiation of the Immunoglobulin heavy chain switch DNA rearrangement event is thought to involve conversion of the target switch region DNA to an accessible state. Accessibility is likely to be mediated by the binding of regulatory proteinsto sequences in or near switch regions. A DNase hypersensitlvity assay was used to recognize possible regions of protein binding in the γ1 switch region of the B cell hybridoma 470.25. A strong DNase hypersensitive site was identified 5'of the tandemly repeated Sγ1 sequences. Data from other laboratories suggest that this hypersensitive siteis associated with switch recombination to γ1 However, the 470.25 cell does not express the γ1 germllne transcript. A second group of DNase hypersensitive sites within the repetitive portion of the γ1 switch region was alsoidentified. A gel retardation assay for protein - DNA interaction revealed a sequence present in several copies in the γ1 switch region that specifically binds nuclear proteins. This binding sequence, SG1BS, contains the octanucleotide sequence ATGCAAAA, a 7/8 match to the transcrlptlonal enhancer octamer motif found in immunoglobulin promoters and the heavy chain enhancer. Binding competition studies of SG1BS demonstrate that both the octamer and flanking sequences are critical for binding. By size- and tissue-distribution, the factors that bind SG1BS are not distinguishable from the previously identified octamer-binding factors OTF-1 and OTF-2. The ability of proteins to bind the Sγ1 octamer motifis increased 2.3-fold upon IL-4 induction of lipopolysaccharide-stlmulated B cells. DNase-hypersensitive sites, sterile transcripts, chromatin accessibility This content is only available as a PDF. Author notes 1Present address: DNAX Research Institute, Palo Alto, CA 94304, USA © Oxford University Press

Journal

International ImmunologyOxford University Press

Published: Feb 1, 1991

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