STRUCTURE OF THE MURINE MB-1 GENE ENCODING A PUTATIVE SIGM-ASSOCIATED MOLECULE

  • 1 July 1990
    • journal article
    • research article
    • Vol. 145  (1) , 337-343
Abstract
Genomic DNA clones containing the B cell-specific murine mb-1 gene were isolated and a 5.6-kb BamH I fragment was characterized. It is 5629 bp long and contains five exons: an exon containing the 5'' untranslated and the coding sequence of the signal peptide, an exon of 294 bp, which contains most of the extracellular sequence of the MB-1 protein, a 119-bp long exon coding mainly for the transmembrane portion, and two exons of 69 bp and 427 bp encoding the cytoplasmic domain and the 3''-untranslated region, respectively. The mb-1 gene does not contain a "TATA box" found in many eukaryotic promoters. The 5''-flanking region has sequence stretches homologous to IgVH 5''-promoter regions and a bcl 2 intron sequence. It contains the decanucleotide sequence (ATGGCAAATA) almost identical to the octamer motif of IgBH promoters. A B cell-specific DNase I-hypersensitive site was found in the 3''-flanking region indicating that this region might be involved in B cell-specific expression of mb-1. Southern blot analysis of genomic liver DNA with the cloned mb-1 cDNA suggests the existence of another mb-1-related gene segment.