The transcription factor, Bright, and immunoglobulin heavy chain expression.

Bright, or B cell regulator of immunoglobulin heavy chain transcription, is a B lymphocyte-specific protein first discovered for its ability to increase immunoglobulin transcription three- to sevenfold in antigen-activated B cells. It interacts with DNA through an ARID, or A/T-rich interaction domain, and is the only member of a previously undescribed family of DNA-binding proteins for which target genes have been identified. The mechanism(s) by which Bright facilitates transcription are unknown. Several proteins that associate with Bright may shed light upon its function. These include the nuclear matrix proteins sp100 and LYSp100B, and suggest that Bright may affect chromatin configuration and nuclear sublocalization. Furthermore, Bruton's tyrosine kinase is required for Bright binding activity, suggesting links between Bright, cell signaling cascades, and X-linked immunodeficiency disease.