Characterization of ABF-1, a novel basic helix-loop-helix transcription factor expressed in activated B lymphocytes.

Proteins of the basic helix-loop-helix (bHLH) family are required for a number of different developmental pathways, including neurogenesis, lymphopoiesis, myogenesis, and sex determination. Using a yeast two-hybrid screen, we have identified a new bHLH transcription factor, ABF-1, from a human B-cell cDNA library. Within the bHLH region, ABF-1 shows a ...
remarkable conservation with other HLH proteins, including tal-1, NeuroD, and paraxis. Its expression pattern is restricted to a subset of lymphoid tissues, Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines, and activated human B cells. ABF-1 is capable of binding an E-box element either as a homodimer or as a heterodimer with E2A. Furthermore, a heterodimeric complex containing ABF-1 and E2A can be detected in EBV-immortalized lymphoblastoid cell lines. ABF-1 contains a transcriptional repression domain and is capable of inhibiting the transactivation capability of E47 in mammalian cells. ABF-1 represents the first example of a B-cell-restricted bHLH protein, and its expression pattern suggests that ABF-1 may play a role in regulating antigen-dependent B-cell differentiation.
Mesh Terms:
Adenovirus E2 Proteins, Amino Acid Sequence, B-Lymphocytes, Base Sequence, Basic Helix-Loop-Helix Transcription Factors, Cloning, Molecular, DNA, DNA-Binding Proteins, Dimerization, Gene Library, Hela Cells, Helix-Loop-Helix Motifs, Humans, Lymphocyte Activation, Molecular Sequence Data, Repressor Proteins, Sequence Alignment, Transcription Factors, Transfection
Mol. Cell. Biol.
Date: Jun. 01, 1998
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