Open AccessA B-Cell-Specific Nuclear Protein That Binds to DNA Sites 5′ to Immunoglobulin Sα Tandem Repeats Is Regulated during Differentiation
Author(s) -
Sean Waters,
Kamal U. Saikh,
Janet Stavnezer
Publication year - 1989
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.9.12.5594-5601.1989
Subject(s) - biology , immunoglobulin heavy chain , immunoglobulin class switching , microbiology and biotechnology , antibody , tandem repeat , immunoglobulin light chain , b cell , dna binding protein , dna , alpha chain , genetics , gene , transcription factor , genome
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.