Genomic structure of the bovine mb-1 gene encoding the Ig-α subunit of the B cell antigen receptor complex

The B cell antigen receptor (BCR) comprises surface immunoglobulin and disulfide-bonded heterodimer of Ig-α and Ig-β chains, which are the products of the mb-1 and B29 genes, respectively. In this study, we describe the isolation and analysis of a 6.2-kb genomic DNA clone containing bovine mb-1 gene encoding Ig-α. Sequence data revealed that the bovine mb-1 gene is composed of five exons and four introns, and that its overall structure is very similar to those of murine and human genes. The 5′ upstream region of the bovine mb-1 gene contained potential protein binding motifs of transcription factors including EBF, Sp1, NF-κB, MUFEts-1 and AP-2. As with the murine and human mb-1 genes, the 5′ region of the bovine mb-1 gene lacked a TATA box. The present study will be useful for understanding the regulated expression of the bovine mb-1 gene at different stages of development and activation as well as in bovine leukemia virus infection.