Bdp, a new member of a family of DNA-binding proteins, associates with the retinoblastoma gene product

We have cloned a gene, BDP, encoding a protein with homology to the retinoblastoma-binding proteins Rbp1 and Rbp2. It also has homology to DNA- binding proteins such as Bright, a B-cell-specific trans-activator, and the Drosophila melanogaster dead ringer gene product. Like MyoD, Bdp binds to the COOH-terminal region of pRb through its conserved region and to hypophosphorylated pRb. It also binds to the MAR of the immunoglobulin heavy- chain locus. Thus Bdp may contribute to the transcriptional regulation of genes involved in differentiation and tissue-specific expression.