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Biomedical subjects

J T August

Publications and source records attributed to J T August.

At least 91 records · Page 5Linked to original sources
PubMed1977

Polypeptides of cells transformed by RNA or DNA tumor viruses.

Proteins solubilized from normal BALB/3T3 cells and BALB/3T3 transformed by simian virus 40 or Kirsten sarcoma virus have been analyzed by two-dimensional gel electrophoresis and tryptic peptide mapping. A large fraction of the polypeptides of the virus-transformed cells, about 30%, were different from normal cells. In contrast to the marked differences between normal and transformed cells, the polypeptides of the DNA and RNA virus-transformed cells were almost identical. These findings were observed with polypeptides stained by Coomassie Blue, or labeled with [14C]glucosamine or [35S]methionine. Pulse-chase analysis showed that most of the polypeptides were stable during 20 hr of incubation. The identity of several polypeptides was confirmed by tryptic peptide mapping.

Cell Line↗
PubMed1977

Biochemical and immunological characterization of the major envelope glycoprotein gp69/71 and degradation fragments from Rauscher leukemia virus.

Analysis of the proteins of Rauscher murine oncornavirus by immunoprecipitation showed that antiserum to the purified envelope glycoprotein of approximately 69,000 and 71,000 daltons (gp69/71) reacted as well with a number of other components of several murine oncornaviruses of approximately 45,000, 32,000, and 15,000 daltons. Polypeptides of similar size were also produced by limited proteolysis of purified gp69/71; these degradation fragments were shown to contain carbohydrate by the incorporation of (3)H from sodium boro[(3)H]hydride after neuraminidase and galactose oxidase treatment. Each of these glycoproteins was isolated by preparative polyacrylamide gel electrophoresis and was analyzed by tryptic peptide mapping. The major virion components of 69,000 and 71,000 daltons were nearly identical, as were the primary degradation fragments. Analysis of the immunological properties of the glycoproteins showed that the 71,000-, 69,000-, and 32,000-dalton glycoproteins behaved similarly with respect to type and group-specific antigenic determinants. In contrast, the 45,000-dalton glycoprotein lacked detectable interspecies and some of the group-specific reactivity. Components of about 45,000 and 32,000 daltons isolated directly from virions were also identified as constituents of the major envelope glycoprotein by immune precipitation and tryptic peptide mapping. These results indicate that all of the examined virion glycoproteins of approximately 71,000, 69,000, 45,000, and 32,000 daltons are derived from the same viral gene and that these lower-molecular-weight glycoproteins can readily be produced from the major envelope glycoprotein.

Carbohydrates↗
PubMed1977

Murine Type C viral envelope glycoprotein gp69/71 and lupus-like glomerulonephritis of New Zealand mice. An immunoperoxidase study.

The location of murine Type C viral envelope glycoprotein antigen in the glomerulonephritic kidneys of NZB and NZB/NZW F1 hybrid mice was analyzed by the indirect immunoperoxidase technique at light and electron microscopic levels. Immune complex deposits of the glycoprotein antigen were present in the glomeruli in mesangial and subepithelial sites. In addition to the glomerular depositions, viral envelope antigen was also present at the brush border of proximal tubular epithelial cells and in lymphoid cells infiltrating the kidneys of these mice.

Animals↗
PubMed1977

Characterization of tumour virus proteins. I. Radioimmunoassay of the P27 protein of avian viruses.

The major structural protein of avian oncornaviruses, a core component of about 27000 daltons, has been measured by radioimmunoassay. The purified protein was labelled with 125Iodine by chloramine-T method. The immune serum titer was defined as the highest serum dilution able to precipitate 50% of the labelled antigen present in the system. Standard competition curve was constructed in order to determine the equivalents of protein, in a system with limiting antibody concentration. In the experimental conditions used, 0.14 ng of AMV-P27 inhibited 50% of 125I-AMV-P27 (1.0 ng) precipitation. The 125I-AMV-P27 vs anti-AMV-P27 system was used to study the competition of normal cells, purified virus suspension, productive cells and supernatant fluids. Most of the chicken embryo fibroblasts showed expression of this viral component. The phenomena of cell transformation, the increase in total protein, and the expression of P27 were studied in rapid transformation of CEF by RSV-SRA.

Alpharetrovirus↗
PubMed1977

Characterization of tumour virus proteins. II. Expression of the protein P30 in transformed productive and non-productive Ki/NRK cells.

The structural protein of murine tumour virus P30 has been measured by radioimmunoassay. The titer of each serum was determined by using as antigen the purified Rauscher viral protein labeled with 125iodine. Standard competition curve was constructed in order to determine the equivalent of protein to inhibit the precipitation reaction under limited antibody concentration. Competition by purifed Kirsten virus suspension, normal rat kidney cells, transformed-productive and transformed non-productive cells were measured in homologous and heterologous system. Type, group and interspecies determinants were characterized using the proper antigen-antibody system. Once the proteins have interspecie determinants, it is possible that we might be able to use some mammalian virus protein as tool to determine the presence of viral protein in human processes.

Animals↗
PubMed1976

Characterization of a virion protein kinase as a virus-specified enzyme.

Antibodies which completely inhibited the enzymatic activity of the protein kinase associated with virions of frog virus were obtained by immunization of rabbits with the purified enzyme. This inhibition provided a specific probe for the frog virus protein kinase, since this antiserum had no inhibitory effect on a variety of other protein kinases, including the activity of uninfected cells, or the protein kinase associated with vesicular stomatitis virus or vaccinia virus cultivated in the same cell line as frog virus. The frog virus protein kinase was characterized as a virus-specified protein on the basis of the following observations: (a) the virion protein kinase was antigenically distinct from essentially all of the protein kinase expressed in uninfected cells; (b) following infection by frog virus more than a 15-fold increase was detected in the specific activity of intracellular protein kinase and most of this activity was antigenically related to the virion enzyme; (c) when frog virus was grown in cells derived from widely different species, the antigenic and biochemical specificities of the virion protein kinase remained identical; and (d) screening of cells infected with different temperature-sensitive mutants of frog virus indicated that certain viral mutants failed to synthesize this protein kinase when cultivated at the nonpermissive temperature.

Adenosine Triphosphate↗
PubMed1976

Purification and properties of a virion protein kinase.

The protein kinase associated with virions of frog virus 3 was purified to apparent homogeneity by ion exchange chromatography and gel filtration. The enzyme protein appeared as a single polypeptide of molecular weight 50,000 to 55,000 as determined by gel filtration, glycerol gradient sedimentation, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and comprised approximately 0.4% of the total virion protein. The activity was classified as a cyclic nucleotide-independent protein kinase as it was not effected by cyclic adenosine 3':5'-monophosphate, cyclic guanosine 3':5'-monophosphate, or inhibited by a cyclic nucleotide-dependent protein kinase inhibitor protein, and utilized GTP as well as ATP as a phosphate donor. The greatest rates of phosphorylation were obtained with acidic phosphoprotein substrates such as casein or phosvitin, although potential physiological substrates for this activity included specific virion polypeptides of frog virus.

Adenosine Triphosphate↗
PubMed1976

Structural proteins of ribonucleic acid tumor viruses. Purification of envelope, core, and internal components.

Murine type C virus structural proteins, the envelope glycopeptides, 30,000 dalton major core protein, and 15,000 dalton internal protein have each been purified to near homogeneity and in high yield from the smae batch of virus by use of phosphocellulose column chromatography and gel filtration procedures. Evidence that these proteins are specified by the viral genome was obtained by competition radioimmunoassay analysis, comparing these polypeptides from Rauscher virus cultivated in a variety of mammalian cell lines; all of the reactive antigenic determinants of these proteins appeared to be virus-specific.

Animals↗
PubMed1976

Analysis of the envelope of Rauscher murine oncornavirus: in vitro labeling of glycopeptides.

The identity and localization of the oligosaccharides of Rauscher murine type C viral glycoproteins have been examined by techniques of in vitro labeling. Terminal sialic acid was labeled with tritium by borohydride reduction after selective periodate oxidation, and galactose was labeled by borohydride reduction after specific enzymatic oxidation of the nonreducing terminal of the sugar. The results were compared with those of protein surface labeling with pyridoxal phosphate or lactoperoxidase catalyzed radioiodination. Examination of the labeled reaction products by polyacrylamide gel electrophoresis in sodium dodecyl sulfate showed that in every case the major component labeled was a glycoprotein of about 70,000 daltons. The identity of this glycoprotein as the virion envelope component was confirmed by immunoprecipitation with mono-specific antiserum prepared against purified Rauscher virus glycopeptides of 69,000 and 71,000 daltons. No other protein or glycoprotein on the surface of the virion was detected, and disruption of virions-before labeling did not reveal additional distinctive glycoproteins. There was minor labeling of sugar residues of other components, but these remain to be characterized and are not now identified as other viral proteins. Studies of the structural organization of virion proteins using the cross-linking reagent methyl-4-mercaptobutyrimidate showed only linkage of the virion envelope or core proteins to themselves. These results indicate that most, if not all, of the oligosaccharides at the surface of Rauscher virus are entities of the 69,000- and 71,000-dalton glycopeptides and that they contain a terminal sialic acid and galactose and a subterminal galactose.

Galactose↗