Exon 2 sequences of an expressed MHC-DRB locus from sheep were examined for polymorphisms in both the antigen-binding regions and the adjacent intronic mixed simple tandem repeat. Twenty-one novel exon 2 Ovar-DRB alleles were identified. Short nucleotide motifs are extensively shared between certain exon 2 regions of Ovar-DRB alleles. The simple repeat variations, the number of different amino ...

The purine nucleoside analog 5,6-dichloro-l-j3-~-ribofuranosylbenzimidazole (DRB) is a selective inhibitor of transcription by RNA polymerase 11. Although a wealth of in vivo studies have suggested that DRB inhibits transcription by enhancing the premature termination of elongating polymerase molecules, in vitro studies to date have been interpreted to suggest that DRB acts at the level of tran...

The kinetics of transport and phosphorylation of the nucleoside analogue 5,6-dichloro-l-~-~-ribofuranosylbenzimidazole (DRB) and the nature of monophosphate metabolites obtained were studied in salivary gland cells of Chironomw tentans. DRB, labeled by exchange with tritiated water, is transported across the plasma membrane, but only monophosphate derivatives emerge in the ethanol-soluble cell...

The primate major histocompatibility complex (Mhc) genes fall into two classes and each of the classes into several families. Of the class II families, the DRB family has a long and complex evolutionary history marked by gene turnover, rearrangement, and molecular convergence. Because the history is not easily decipherable from sequences alone, Alu element insertions were used as cladistic mark...

5,6-Dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) inhibits RNA synthesis in L-929 cells (mouse fibroblast line) and HeLa cells (human epitheloid carcinoma line) within 2 min of addition of the compound to the medium. By removing DRB from the medium, the inhibition is promptly and completely reversed after treatment of cells for as long as 1 h or even longer. The inhibitory effect of DRB on...

DRB triphosphate inhibits activity of isolated RNA polymerase B, and, to a lesser extent, that of polymerase A. The same holds true for transcription in isolated nuclei. It does not act as an initiation inhibitor. In all cases, high concentrations of DRB triphosphate are required. Cells do not phosphorylate DRB to a measurable extent. hn RNA resistant to DRB is initiated with both ATP and GTP i...

The rhesus macaque is an important model in preclinical transplantation research and for the study of chronic and infectious diseases, and so extensive knowledge of its MHC (MhcMamu) is needed. Nucleotide sequencing of exon 2 allowed the detection of 68 Mamu-DRB alleles. Although most alleles belong to loci/lineages that have human equivalents, identical Mhc-DRB alleles are not shared between h...

In the present study, water buffalo MHC (Bubu)-DRB cDNA was cloned and characterized. The 1022 base long-amplified cDNA product encompassed a single open reading frame of 801 bases that coded for 266 amino acids. The Bubu-DRB sequence showed maximum homology with the BoLA-DRB3*0101 allele of cattle. A total of seven amino acid residues were found to be unique for the Bubu-DRB sequence. The majo...

This study characterises the expressed MHC class II DRB gene and its genetic variation in exon 2 among 59 Alpine chamois (Rupicapra r. rupicapra) from several locations in the Eastern Alps plus one population in the Western Alps. The expressed DRB gene contains all the expected characteristics including all of the conserved residues found in other mammalian species. The isolated expressed DRB g...