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Biomedical subjects

D Gallwitz

Publications and source records attributed to D Gallwitz.

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

Fate of histone messenger RNA in mengovirus-infected Ehrlich ascites tumor cells.

Histone mRNA was isolated from mengovirus-infected Ehrlich ascites tumor cells at various times postinfection and quantitated in a reticulocyte cell-free protein-synthesizing system. The amount of translatable histone mRNA decreases during the first hour postinfection by 30%, rises during the following 1-1.5 h by 10-15%, drops progressively in the further course of infection, and reaches 20% of the control at the end of the infectious cycle (8-9 h postinfection). On the basis of the relative histone mRNA contents, the histone-synthesizing potentials of mengovirus-infected Ehrlich ascites tumor cells are substantially higher throughout infection than actually expressed in vivo. This result indicates that the virus-induced shutoff of histone synthesis is not directly the consequence of inactivation or degradation of histone mRNA. Most of the histone mRNA recovered from mengovirus-infected Ehrlich ascites tumor cells is bound to ribosomes. Late in infection, certain mRNAs are co-isolated with histone mRNAs, very likely due to loss or shortening of poly(A) occurring after release of the mRNAs from polyribosomes.

Animals↗
PubMed1977

Fate of histone messenger RNA in synchronized HeLa cells in the absence of initiation of protein synthesis.

The fate of cytoplasmic histone mRNA was studied under conditions in which initiation of protein synthesis in synchronized HeLa cells is S phase was blocked by increasing the osmolarity of the growth medium with NaCl. In contrast to the interruption of DNA replication with hydroxyurea, which results in an exponential degradation of translatable histone mRNA with a half-life of about 10-13 min, blocking the initiation of protein synthesis leads to only a marginal loss of biologically active histone mRNA in the cytoplasm. When the initiation of protein synthesis was interrupted by treating cells with 150 mM NaCl, 40-50% of the total cytoplasmic histone mRNA previously translated in polyribosomes appears in the cytoplasm integrated into mRNA-protein particle(s) sedimenting between 15 S and 30 S. On the other hand, in untreated S-phase cells or in cells blocked with hydroxyurea only 3-6% of the total translatable histone mRNA is found in the cytoplasm not bound to ribosomes or their subunits. In addition, the degradation of histone mRNA in hydroxyurea-blocked S-phase cells is prevented when the initiation of protein synthesis is inhibited with NaCl. These studies clearly indicate that the inhibition of initiation of protein synthesis per se is not the cause for the rapid degradation of cytoplasmic histone mRNA observed when DNA replication is turned off and that the inactivation of these mRNAs is a process dependent on continuous protein synthesis.

Cell Division↗
PubMed1976

Initiation of synthesis of N-terminal acetylated histones with methionine.

The studies presented were undertaken to clarify the unsettled question whether the synthesis of histones with a N-acetylserine residue at the amino terminal end is initiated with methionine. Histones were synthesized in vitro in a rabbit reticulocyte lysate, primed with a mRNA preparation from ascites cells. Initiation of polypeptide synthesis was investigated by using N-formyl[35S]met-tRNAfMet from yeast to label the N-termini. N-Formylmethionine was incorporated into histones H1 and H4 whose N-terminal amino acid is alpha-N-acetylserine. By comparison of tryptic peptides derived from these two histones labeled either with methionine or formylmethionine and from Edman degradation it is shown that N-terminal acetylated histones are initiated with methionine, as is the case for other eukaryotic and bacterial proteins.

Amino Acid Sequence↗