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Biomedical subjects

R Devos

Publications and source records attributed to R Devos.

86 records · Page 5Linked to original sources
PubMed1976

Addition by ATP: RNA adenylyltransferase from Escherichia coli of 3'-linked oligo(A) to bacteriophage Qbeta RNA and its effect on RNA replication.

An oligo(A) or poly(A) segment was added in a stepwise fashion to the 3'-end of bacteriophage Qbeta-RNA with the aid of ATP : RNA adenylyltransferase from Escherichia coli. Nearly all RNA molecules, present in the reaction mixture, could be polyadenylated. For tail lengths not exceeding 200 nucleotide residues, the physical properties of Qbeta-RNA-poly(A) were found to be only slightly different from those of the original RNA. The polyadenylated RNA was purifed by affinity chromatography. The properties of Qbeta-RNA with oligo(A) tails of different average lengths were investigated in the in vitro replication reaction. Almost complete abolishment of template activity, even by short oligo(A) stretches, was found. Furthermore, polyadenylated Qbeta-RNA inhibited the normal replication reaction of Qbeta-RNA by removal of host factor HFI, in the same way as does free poly(A).

Adenosine Monophosphate↗
PubMed1976

The enzymic addition of poly(A) to the 3'-end of RNA using bacteriophage MS 2 RNA as a model system.

ATP : RNA adenyltransferase, purified from Escherichia coli, was used to add a series of adenosine residues to the 3'-end of MS2RNA. Incubations of the order of a few minutes at 37 degrees C were sufficient for synthesis of a short poly(A) chain that did not appreciably alter the hydrodynamic or electrophoretic properties of MS2 RNA. The size of the poly(A) tails was estimated by gel electrophoresis after prior hydrolysis of the primer RNA with pancreatic ribonuclease. These results were in good agreement with the values calculated on the basis of the relative amount of incorporated AMP. After the addition of a short poly(A) tail, approximately 50% of the treated material binds specifically to an oligo(dT)-cellulose column. The majority of the recovered poly(a)-containing RNA was still intact, as shown by analysis on polyacrylamide gel. After incubations beyond 6 min, slowly sedimenting material, also showing reduced electrophoretic mobility, was formed. Presumably this material corresponds to RNA chains to which long poly(A) tails are linked.

Centrifugation, Zonal↗
PubMed1975

Readenylation of polyadenylate-free globin messenger RNA restores its stability in vivo.

Using an ATP:RNA adenyltransferase from Escherichia coli, a polyadenylic sequence was resynthesized onto rabbit globin mRNA from which the poly (A) segment had been previously removed. Conditions for obtaining a homogenous reconstituted globin mRNA preparation containing 30 adenylic residues per message molecule were determined. The reconstituted globin mRNA was microinjected into Xenopus laevis oocytes. Its stability was very similar to that of native mRNA.

Adenine Nucleotides↗
PubMedDate not supplied

Isolation and characterization of a human fibroblast interferon gene and its expression in Escherichia coli.

Human fibroblasts were induced for interferon synthesis, and the mRNA coding for interferon was partially purified. On this basis, double-stranded DNA copies were synthesized enzymatically and were inserted into cloning vehicles. A large collection of colonies containing chimeric plasmids was obtained. An RNA selection method was used for the identification of several individual clones containing the human fibroblast interferon (IFN-beta) cDNA. From the nucleotide sequence of the cloned structural gene, the primary structure of the mRNA and, hence, of the protein itself was deduced. IFN-beta is a polypeptide 166 amino acids long and contains a single site for N-glycosylation; IFM-beta is normally made as a preinterferon containing a signal sequence that is 21 amino acids long. The interferon gene was inserted into an expression plasmid under thermoinducible control of the phage lambda PL promoter. this allowed the synthesis of polypeptides in the bacteria, which for all physicochemical, biological, and immunologic properties tested closely resembled authentic IFN-beta.

Amino Acid Sequence↗
PubMedDate not supplied

Organization and chromosomal localization of the human interleukin 5 receptor alpha-chain gene.

The gene for the hIL-5R alpha subunit, which is present in a single copy in the human genome, has been analysed in detail. It is located on chromosome 3 in the region 3p26. The gene organization reflects its relationship to the cytokine/haematopoietin receptor superfamily. Three introns are located in the 5' untranslated region. The subsequent exons determine the functional domains of the hIL-5R alpha protein: the signal peptide, three fibronectin type III-like (FN-like) modules, each built up by two exons, the membrane anchor and two exons forming the cytoplasmic tail, the first of which contains the proline cluster region. In addition, a specific exon generating a soluble isoform is located before the membrane anchor exon. This specific exon contains an in frame TAA stop codon, followed by a polyadenylation signal. Hence, a normal splicing event leads to a soluble IL-5R alpha variant, whereas alternative splicing is required for cell membrane anchoring. A second area of alternative splicing is found in the 5' leader sequence, and possibly relates to the presence of short open reading frames preceding the main ATG. All intron-exon junctions meet the GT-AG rule. The gene structures of all cytokine/haematopoietin receptors documented so far have also been compared with respect to intron phasing. This shows that all introns between the FN-III-like modules are of the +1 type, but in addition, splice sites within the Cys-module and WS-WS-module are invariably of the +2 and 0 type, respectively.

Amino Acid Sequence↗