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Results for “Peptide Chain Initiation, Translational”

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At least 19 recordsLinked to original sources
PubMed1978

Inhibition of globin synthesis by rabbit reticulocyte rRNAs.

The effect of concentration of rabbit reticulocyte rRNAs on the translation of rabbit globin mRNAs was studied by using a rabbit reticulocyte lysate system. Globin synthesis was studied using L-[U-14C]leucine. Both the 18S and 28S rRNA inhibited globin synthesis. The 18S rRNA inhibited the synthesis of alpha-globin chain more than that of beta chain, but the 28S rRNA inhibited the synthesis of alpha- and beta-chains almost equally. Nascent chains prelabelled with [14C]Leu or f[35S]Met were released at various concentrations of rRNAs. Release of the nascent chains was not inhibited at various concentrations of rRNAs. The ratios [14C]alpha/[14C]beta and [35S]alpha/[35S]beta in the released chains were almost constant at various concentrations of rRNAs. It therefore appears that the inhibition of globin synthesis by these rRNAs was at the step of initiation.

Animals↗
PubMed1978

Models for mRNA translation: theory versus experiment.

Three models for mRNA translation are discussed in the light of available experimental data. It is concluded that the elongation rates vary along a messenger, possibly as a result of a coupling between ribosome movement and mRNA secondary structure. Some promising areas of further experimentation are indicated.

Alpha-Globulins↗
PubMed1979

A kinetic model of protein synthesis. Application to hemoglobin synthesis and translational control.

We present a kinetic model of protein synthesis which encompasses initiation, elongation, and termination parameters. We have investigated the dependence of the total rate of protein synthesis and the size of the translating polysomes on each of these parameters and in particular on the level of active 40 S ribosomes and initiation factors. This model qualitatively fits experimental data for the ratio of alpha- to beta-globin synthesis in reticulocytes, both under normal conditions and in the presence of inhibitors of chain initiation. This model has also been used to examine the effect that limiting amounts of certain tRNAs might have on the total rate of protein synthesis. In addition, the role of initiation factor discrimination and mRNA length are examined with respect to the differential translation of mRNAs.

Animals↗
PubMed1979

Acidic ribosomal proteins from eukaryotic cells. Effect on ribosomal functions.

Precipitation of Saccharomyces cerevisiae ribosomes by ethanol under experimental conditions that do not release the ribosomal proteins can affect the activity of the particles. In the presence of 0.4 M NH4Cl and 50% ethanol only the most acidic proteins from yeast and rat liver ribosomes are released. At 1 M NH4Cl two more non-acidic proteins are lost from the ribosomes. The release of the acidic proteins causes a small inactivation of the polymerizing activity of the particles, additional to that caused by the precipitation itself. The elongation-factor-2-dependent GTP hydrolysis of the ribosomes is, however, more affected by the loss of acidic proteins. These proteins can stimulate the GTPase but not the polymerising activity when added back to the treated particles. Eukaryotic proteins cannot be substituted for bacterial acidic proteins L7 and L12. We have not detected immunological cross-reaction between acidic proteins from Escherichia coli and those from yeast, Artemia salina and rat liver or between acidic proteins from these eukaryotic ribosomes among themselves.

GTP Phosphohydrolase-Linked Elongation Factors↗
PubMed1979

Protein synthesis and aging: studies with cell-free mammalian systems.

A cell-free system devoid of polysomes, which translates natural mRNA, has been prepared from rat liver. It contains ribosomal subunits, ribosomes, aminoacyl-tRNA synthetases, tRNAs, and protein factors necessary for translation. Protein synthesis required an energy-generating system, mRNA, and 3 mM Mg2+ concentration, and it was inhibited by 7-methylguanylic acid. The total extent and the rate of protein synthesis were approximately 30% greater when the translating system was prepared from livers of 3-month-old rats, as compared to 30-month-old rats. A ribosome-free fraction containing the protein factors required for translation was also prepared from 3-month-old and 30-month-old rat livers and brains, by extraction with 0.5 M KCl. The high-salt extracts were analyzed for elongation factors EF-1 and EF-2 in a poly(U) translating system. Although the activity of EF-2 was similar in preparations from young and old rats, the EF-1 activity in the 3-month-old rat livers and brains was 30 to 40% greater than in 30-month-old animals. The protein synthesizing activity of high salt-washed ribosomes stripped of endogenous peptidyl-tRNA and mRNA, from livers and brains of young and old animals, was the same.

Aging↗