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Biomedical subjects

H Diggelmann

Publications and source records attributed to H Diggelmann.

72 records · Page 4Linked to original sources
PubMed1979

Biosynthesis of an unglycosylated envelope glycoprotein of Rous sarcoma virus in the presence of tunicamycin.

Cells stably infected with Rous sarcoma virus were treated with tunicamycin to prevent the glycosylation of the precursor (pr92gp) to the two viral envelope glycoproteins gp85 and gp35. Pretreatment of the cells for 4 h with the antibiotic resulted in a 90% reduction in [3H]mannose incorporation into total cellular glycoproteins, intracellular viral glycoproteins, and released virus particles. Protein synthesis and virus particle formation were not significantly affected by the treatment. A new polypeptide made in the presence of the drug was identified by immunoprecipitation of pulse-labeled cell lysates with monospecific anti-gp85 and anti-gp35 sera. This polypeptide, migrating on sodium dodecyl sulfate-polyacrylamide gels as a molecule of 62,000 daltons (pr62), contained no [3H]mannose, was labeled with [S35]methionine and [3H]arginine, could not be chased into the higher-molecular-weight glycosylated form, and contained the same [3H]arginine tryptic peptides as pr92gp. The unglycosylated pr62 was still detectable 2 h after the pulse labeling of the cells. The lack of glycosylation of pr62 did not seem to reduce its stability. No clear evidence for the incorporation of this molecule or its cleavage products into viral particles could be obtained. To code for an envelope polypeptide of 62,000 daltons, only about 1,500 nucleotides or 15% of the total coding capacity of the virus are needed.

Avian Sarcoma Viruses↗
PubMed1974

Estimation of the number of genes coding for the constant part of the mouse immunoglobulin kappa light chain.

As previously shown, purified 14S RNA of mouse myeloma MOPC-41 forms a single peak on sucrose gradients and gel electrophoresis and codes for a single polypeptide chain, the immunoglobulin light chain produced by the same myeloma in vivo. This 14S mRNA was used for the enzymatic synthesis of DNA (cDNA) which is complementary to the RNA template. A DNA fraction was isolated which has an average size of 300 nucleotides. Kinetic studies of the hybridization of the 14S RNA with the cDNA indicate that about 40% of the RNA consists of a single RNA sequence. From the size of the cDNA fraction and from the direction of DNA synthesis, it can be concluded that the cDNA includes the sequence complementary to the constant region of light chain mRNA. This radioactive cDNA was used for DNA.DNA reannealing experiments with unlabeled DNA from mouse liver or myeloma tumor in 3 x 10(6)-fold excess. This allowed the determination of the number of copies in the mouse genome of those sequences represented in the cDNA. The data show no significant reiteration in either liver or myeloma DNA and suggest that the gene coding for the constant part of immunoglobins is present in the haploid genome in one to five copies. Furthermore, this gene is not "amplified" in nuclear DNA of myeloma plasmocytes.

Animals↗
PubMed1973

Demonstration of globin messenger sequences in giant nuclear precursors of messenger RNA of avian erythroblasts.

Highly purified globin mRNA from ducks was copied with RNA-directed DNA polymerase from avian myeloblastosis virus into anti-messenger DNA. With excess RNA, more than 90% of this DNA annealed back to its template with a C(o)t/2 value of 7.5 x 10(-4) mol.sec. liter(-1); the melting temperature of the hybrid was 86 degrees . Giant nuclear RNA fractions with sedimentation coefficients of more than 50 S formed hybrids of almost equal stability at C(o)t/2 values of 0.05-0.42 mol.sec. liter(-1), indicating amRNA content of 0.3-1.5%. 12S RNA from the same polyribosomes and nuclear giant RNA from HeLa cells did not cross-hybridize. Although a large part of the giant RNA broke down in 99% dimethylsulfoxide gradients, RNA fractions sedimenting faster than 28S rRNA still were found to consist of up to 0.03% globin mRNA sequences. Thus, the mRNA sequences are contained in the covalent structure of giant nuclear precursors, which are termed precursor-mRNA.

Animals↗