title: A B-cell-specific nuclear protein that binds to DNA sites 5' to immunoglobulin S alpha tandem repeats is regulated during differentiation.
abstract: Immunoglobulin heavy-chain switching is effected by recombination events between sites associated with tandemly repeated switch sequences located 5' to immunoglobulin heavy-chain genes. Using the band mobility shift assay, we have identified two distinct sites 5' to the alpha heavy-chain switch sequence with affinity for a single B-cell-specific DNA-binding protein, S alpha-BP. S alpha-BP was present in nuclear extracts from pre-B and B cells but was not detected in extracts from plasmacytomas, B-cell hybridomas, T-cell lymphomas, or a macrophage cell line. It was also not detectable in other nonlymphoid cells tested. Evidence suggests there are S alpha-BP-binding sites near other immunoglobulin switch sequences. As with the S alpha sites, these sites appear to be distinct from the consensus tandem repeats characteristic of immunoglobulin switch sequences. The possible functions of S alpha-BP on contacting its binding sites are discussed in the context of immunoglobulin heavy-chain switch recombination.
authors.affiliation: Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester 01655.
authors.forename: S H
authors.initials: SH
authors.lastname: Waters
authors.forename: K U
authors.initials: KU
authors.lastname: Saikh
authors.forename: J
authors.initials: J
authors.lastname: Stavnezer
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005803:Genes, Immunoglobulin; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D008745:Methylation; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009710:Nucleotide Mapping; D011995:Recombination, Genetic; D015183:Restriction Mapping
chemical_list: D004268:DNA-Binding Proteins; D007143:Immunoglobulin Heavy Chains; D009687:Nuclear Proteins; D004247:DNA