A B-cell-specific nuclear protein that binds to DNA sites 5' to immunoglobulin S alpha tandem repeats is regulated during differentiation

UMMS Affiliation

Department of Molecular Genetics and Microbiology

Publication Date


Document Type



Animals; B-Lymphocytes; Base Sequence; Cell Line; Cloning, Molecular; DNA; DNA-Binding Proteins; *Genes, Immunoglobulin; Immunoglobulin Heavy Chains; Methylation; Molecular Sequence Data; Nuclear Proteins; Nucleotide Mapping; Recombination, Genetic; Restriction Mapping


Life Sciences | Medicine and Health Sciences | Women's Studies


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.

DOI of Published Version



Mol Cell Biol. 1989 Dec;9(12):5594-601.

Journal/Book/Conference Title

Molecular and cellular biology

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