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Biomedical subjects

J Content

Publications and source records attributed to J Content.

At least 145 records · Page 8Linked to original sources
PubMed1980

Expression of human fibroblast interferon gene in Escherichia coli.

The human fibroblast interferon gene was inserted in a thermoinducible expression plasmid under control of the phage lambda PL promoter. The primary translation products predicted on the basis of the plasmid constructions were hybrid proteins starting with beta-lactamase or phage MS2 polymerase information followed by the total preinterferon. On induction, antiviral activity, whose physico-chemical, immunological and biological characteristics closely corresponded to those of authentic human fibroblast interferon, was synthesized. Processing to a size compatible with mature but unglycosylated authentic product was observed.

Biological Assay↗
PubMed1980

Isolation and structure of a human fibroblast interferon gene.

Chimaeric plasmids containing double-stranded cDNA copies of mRNA induced in human fibroblasts by poly I . C were screened by an RNA selection method. A series of clones to which human fibroblast interferon mRNA selectively hybridized was identified. From the nucleotide sequence of the gene, the complete amino acid sequence of human fibroblast interferon was deduced. The protein is 166 amino acids long and is preceded by a 21-amino acid signal sequence.

Amino Acid Sequence↗
PubMed1980

Intracellular glycosylation of influenza hemagglutinin: the effect of glucosamine.

The intracellular glycosylation of influenza virus hemagglutinin has been studied in calf kidney primary cultures infected with influenza virus A/NWS (H0N1). Intermediate glycosylated forms were obtained by the addition of glucosamine to the culture medium; they were characterized after [35S]-methionine labelling by their precursor relationship, by immunoprecipitation and peptide mapping. The underglycosylated hemagglutinins were distributed in classes of discrete molecular weight indicating that glycosylation occurred in a stepwise manner. A total of 8 different bands, suggesting 7 glycosylation sites, was obtained under conditions of both complete and incomplete glycosylation.

Animals↗
PubMed1980

Abnormal behavior of interferon-induced enzymatic activities in an interferon-resistant cell line.

Interferon induces two double-stranded RNA-dependent enzymatic activities: an oligoisoadenylate synthetase that converts ATP to ppp(A2'p)n5'A, and a protein phosphokinase. We have explored the level and inducibility of these two enzymes in a human cell line (HEC-1) totally insensitive to both the antiviral and the anticellular actions of interferon. The activities of both enzymes are high in untreated cells and only minor changes occur after treatment with interferon, even at high concentrations. Interferon-treated HEC-1 cells do not contain an inhibitor of the oligoisoadenylate synthetase activity. The products of this HEC-1 oligoisoadenylate synthetase consist mainly of dimers, trimers, and tetramers as found in other cell lines after interferon treatment. The synthetase level is unaffected by treating the cells with anti-interferon antiserum, indicating that the results cannot be explained by a spontaneous low production of interferon by these cells. Furthermore, virus multiplication is not inhibited, even after treatment with interferon. These observations suggest that either the two enzymatic activities do not suffice for the establishment of an antiviral state in vivo or that a regulatory control mechanism, lost in these cells and common for both enzymes, is required for the expression of the antiviral action of interferon. This might explain both the constitutivity of the two enzymes and the interferon resistance observed.

2',5'-Oligoadenylate Synthetase↗
PubMed1978

Comparison of interferon action in interferon resistant and sensitive L1210 cells.

Translation inhibition, leu-tRNA aminoacylation and double-stranded RNA and ATP dependent phosphorylation were examined in interferon-treated and control cell-free lysates of leukaemic mouse L 1210 R and L 1210 S cells. No differences were observed between the respective interferon-treated and control cell-free extracts, except for the presence of an enhanced 67K dalton phosphoprotein fraction in interferon-treated L 1210 S cell-free extracts. In non-responding cell-free lysates, the lack of stimulation of a 67K dalton phosphoprotein fraction cannot be explained by the presence of an increased level of some inhibitory activity, such as a phosphatase.

Animals↗
PubMed1978

Peptide mapping characterization of viral proteins generated in a cell-free coupled system for the transcription and translation of influenza virus mRNA.

In a coupled cell-free system for the transcription and translation of the influenza mRNA's, containing detergent-disrupted purified NWS influenza virion and a micrococcal nuclease-preincubated rabbit reticulocyte lysate, five unglycosylated viral proteins (NS1, M, NP, P1, and P3) were easily produced and isolated. Their identification was based on the electrophoretic separation of peptide fragments resulting from their partial digestion with proteases of restricted specificity (D.W. Cleveland, S. G. Fisher, N. W. Kirschner, and U. K. Laemmli, J. Biol. Chem. 252:1102-1106, 1977).

Cell-Free System↗
PubMed1977

Cell-free coupling of influenza virus RNA transcription and translation.

A cell-free coupled system for the transcription and translation of fowl plague virus RNA is described. The system utilizes a new nuclease-preincubated rabbit reticulocyte lysate that has a high sensitivity to exogenous mRNA and a very low level of nuclease activity. Translation of the viral proteins in the coupled system is strictly dependent upon the viral transcriptase activity. In the coupled system the optimal concentration of magnesium is intermediate between the optimum for transcription and that for translation. Translation of the viral proteins seems faithful. The products represent the major viral peptides M and NP and two peptides with the same electrophoretic mobility as HA and P2. Viron NA is not resolved in the kind of polyacrylamide gels described. Proteins M and NP were immunoprecipitable with monospecific antisera. It is concluded that the virion-associated RNA polymerase transcribes the negative-stranded segments of the viral genome coding for these major structural proteins into fully functional mRNA's.

Animals↗
PubMed1976

Cell-free translation of influenza virus mRNA.

Cytoplasmic poly (A)-rich RNA extracted from fowl plague virus-infected cells was found to program efficiently the translation of two major peptides in the wheat germ cell-free system. These peptides have the same electrophoretic mobility, on polyacrylamide gels, as the two major virion proteins M and NP. [35S] methionine tryptic peptide analysis by one-dimensionalthin-layer ionophoresis and finger printing by two-dimensional thin-layer ionophoresis and chromatography show a high degree of similarity between the two in vitro products and the authentic viral proteins M and NP. Although virion RNA is devoid of any poly (A) sequence, it is confirmed here that the viral complementary cytoplasmic RNA contains poly (A) stretches of varying lengths. Intact purified virion was found to promote the synthesis of very low amounts of the same NP and M proteins in this cell-free system. Quantitative aspects of data would indicate that this is due to minute amounts of complementary viral RNA associated with the virion or with the virion RNA itself. In conclusion, it is shown diectly by cell-free translation of authentic viral products that the influenza virion is "negative stranded" (Baltimore, 1971), at least for its two major structural proteins.

Cell-Free System↗
PubMed1975

Blocks in elongation and initiation of protein synthesis induced by interferon treatment in mouse L cells.

Synthesis of polypeptide chains coded by exogenous messenger RNAs is inhibited in cell-free extracts from interferon-treated mouse L cells, due to a "deficiency" in some specific tRNA species. A detailed analysis shows that polypeptide chain elongation is blocked and incomplete chains are formed. After a few minutes, however, initiation of new polypeptide chains is also blocked. Messenger RNA still binds to ribosomes but initiator Met-tRNA(FMET) binding is inhibited. The block in initiation appears to be secondary to the block in elongation.

Animals↗
PubMed1972

Structure of the ribonucleoprotein of influenza virus.

The ribonucleoprotein (RNP) internal components of influenza virus were separated into distinct size classes by sedimentation in glycerol gradients and examined by electron microscopy by using positive staining with uranyl acetate. The large RNP have a peak in length distribution at 90 to 110 nm, the medium, at 60 to 90 nm, and the small, at 30 to 50 nm. These lengths can be correlated with the estimated molecular weights of the ribonucleic acids contained in the various RNP size classes. The RNP structure appears to consist of a strand which is folded back on itself and coiled in a regular double-helical arrangement.

Animals↗