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H Oppermann

Publications and source records attributed to H Oppermann.

47 records · Page 3Linked to original sources
PubMed1976

Control of peptide chain initiation in uninfected and virus infected cells by membrane mediated events.

Initiation of protein synthesis in tissue culture cells is rapidly inhibited or blocked by addition of either DMSO, ethanol, TPCK, cytochalasin B, or sucrose to the growth medium. In contrast, these agents do not interfere with the initiation of protein synthesis in cell-free extracts to a comparable extent. These results support the hypothesis that protein synthesis in tissue culture cells can be influenced by membrane mediated events. Translation of viral mRNA in RNA virus infected cells is resistant to a number of these inhibitors of peptide chain initiation and proceeds under conditions where translation of host mRNA is almost completely suppressed. It appears that viral mRNA possesses a greater ability than host mRNA to form mRNA-ribosome initiation complexes when the overall rate of peptide chain initiation is reduced. This observation has led to a number of predictions concerning the strategy of virus directed suppression of host mRNA translation. Under optimal growth conditions protein synthesis appears to be regulated mainly, but not exclusively, by the amount of the mRNA available for translation. However, when cellular growth and/or the overall rate of peptide chain initiation is restricted, control of protein synthesis at the translational level becomes decisive with the translation of each mRNA species proceeding with its own characteristic efficiency most probably as a result of inherent differential affinities of individual mRNA species for ribosomes.

Cell Line↗
PubMed1976

Individual translational efficiencies of SV40 and cellular mRNAs.

The technique of selective inhibition of peptide chain initiation by growth medium hypertonicity was adapted for cell monolayer cultures and applied to a study of protein synthesis in SV40 infected BSC-1 cells. The translational efficiences for individual peptide chain initiation sites on SV40 mRNAs were determined and compared to those for cellular mRNA species under conditions of a reduced rate of peptide chain initiation. The SV40 mRNAs show different translational efficiences. The results indicate that the synthesis of the SV40 proteins VP1, 2 and 3 are initiated independently and with different rates on viral mRNA(s). It is proposed, therefore, that VP2 is not a precursor for VP3.

Cell Line↗
PubMed1976

On the regulation of protein synthesis in vaccinia virus infected cells.

All eukaryotic mRNA species show a characteristic individual translational efficiency under conditions of restricted polypeptide chain initiation caused by an increase in the osmolarity of the growth medium. In vaccinia virus infected L cells or HeLa cells virus mRNAs can be grouped into classes on the basis of their relative labelling under standard and hypertonic conditions. Under the latter conditions, most of the "early" mRNAs possess very high translational efficiencies, most of the "intermediate" mRNAs show an intermediate efficiency and the most prominent "late" mRNAs show a translational efficiency which is lower than that of other virus mRNAs but still higher than the average cellular mRNA. Late in the infection cycle virus mRNAs with a relative low translational efficiency are preferentially translated under standard growth conditions whereas "early" virus mRNAs which are still present and which show a higher translational resistance to hypertonic conditions are not translated. These results indicate a unique translational control operating late in the growth cycle of vaccinia virus.

HeLa Cells↗
PubMed1975

Poliovirus-induced infectious double-stranded RNA: Effect of RNA-degrading enzymes.

The infectivity of replicative form RNA (RF-RNA) isolated from poliovirus-infected HeLa cells is completely resistant to the action of T-1 RNase but decreases after exposure to RNase A in the presence of 0.3 M NaCl. Under these conditions neither enzyme produces single-stranded nicks in RF-RNA. Three endonuclease-free exonuleases (RNase II, polynucleotide phosphorylase and spleen phosphodiesterase) rapidly destroy the infectivity of single-stranded RNA, but do not alter the infectivity of RF-RNA. It is concluded that RF-RNA does not contain single-stranded ends essential for infectivity. Indirect evidence suggests that all or most of the poly A region at the 3' end of the plus strand of infectious RF-RNA is base-paired to a poly U region at the 5 end of the minus strand.

Base Sequence↗
PubMed1975

Selective blockage of initiation of host protein synthesis in RNA-virus-infected cells.

Poliovirus mRNA and mRNA transcribed from vesicular stomatitis virus and reovirus genomes efficiently direct protein synthesis in vivo under experimental conditions where the initiation of host protein synthesis is selectively blocked. The selective blockage of host peptide chain initiation after exposure to hypertonic medium indicates that the translation of viral mRNA is more efficiently initiated than is the translation of host mRNA. It further suggests that virus directed suppression of host protein synthesis could proceed by a mechanism involving a nonspecific decrease in the rate of peptide chain initiation. Exposure of infected cells to hypertonic medium provides a unique tool with which to study early events in the infectious cycle by permitting the efficient unmasking of virus-specific poly-peptide synthesis.

Animals↗
PubMedDate not supplied

Structure of human factor VIII.

The deduced amino acid sequence of human factor VIII, obtained from the DNA sequence, predicts a mature polypeptide of 2,332 amino acids containing a triplicated domain structure. The polypeptide has 35% sequence homology with the copper-binding plasma protein, ceruloplasmin. Determination of the thrombin cleavage sites in plasma-derived factor VIII polypeptides allows prediction of the domains involved in the associated activation and inactivation of the protein.

Amino Acid Sequence↗