scholarly journals Protein synthesis in the liver of rats injected with cholesteryl 14-methylhexadecanoate

1972 ◽  
Vol 129 (2) ◽  
pp. 367-372 ◽  
Author(s):  
E. Komárková ◽  
J. Hradec
Keyword(s):  
Protein Synthesis ◽  
Liver Tissue ◽  
Regulatory Mechanism ◽  
Relative Content ◽  
Time Intervals ◽  
Peptidyl Transfer ◽  
Significant Stimulation ◽  
Peptide Elongation

1. Rats were injected intraperitoneally with cholesteryl 14-methylhexadecanoate and killed after various intervals of time up to 3 days; ribosomes and cell sap were isolated from their liver tissue. These fractions were tested for their ability to participate in protein synthesis. 2. Protein synthesis in complete systems containing ribosomes, cell sap and all necessary cofactors was significantly enhanced at 12 and 72h after the injection and significantly inhibited at 24h. At early times after injection isolated ribosomes had a slightly enhanced ability to bind nRNA. Peptide-elongation processes (i.e. binding of aminoacyl-tRNA to ribosomes, peptidyl transfer and polyphenylalanine synthesis) showed significant stimulation or inhibition depending on the time after injection of the ester. 3. A correlation was found between the ability of cell sap to stimulate polyphenylalanine synthesis and the relative cholesteryl 14-methylhexadecanoate content in the postmicrosomal supernatant at different time-intervals after administration of the ester. No significant changes were found in its content in the whole liver tissue. 4. Since the injected ester has previously been shown to accumulate in some enzymic fractions, the changes in its relative content may represent a regulatory mechanism modulating the rate of protein synthesis.

scholarly journals Nature of the stimulation of biogenesis of cholesterol in the liver by noradrenaline

1977 ◽  
Vol 162 (3) ◽  
pp. 493-499 ◽  
Author(s):  
R George ◽  
T Ramasarma
Keyword(s):  
Protein Synthesis ◽  
Adrenergic Receptors ◽  
De Novo ◽  
Direct Action ◽  
Time Intervals ◽  
Coa Reductase ◽  
Short Time ◽  
Stimulation Of

1. Administration of noradrenaline increased the incorporation of [1-14C]acetate into hepatic sterols and the activity of liver microsomal 3-hydroxy-3-methylglutaryl-CoA reductase. 2. The stimulation was observed at short time-intervals with a maximum at 4h and was progressive with increasing concentrations of noradrenaline. 3. Protein synthesis de novo was a necessary factor for the effect. 4. The stimulatory effect was not mediated through the adrenergic receptors, but appears to involve a direct action of the hormone within the hepatocyte.

Insulin stimulation of protein synthesis in cultured skeletal and cardiac muscle cells

1982 ◽  
Vol 243 (1) ◽  
pp. C81-C86 ◽  
Author(s):  
J. Airhart ◽  
J. A. Arnold ◽  
W. S. Stirewalt ◽  
R. B. Low
Keyword(s):  
Protein Synthesis ◽  
Specific Activity ◽  
Muscle Cells ◽  
Cell Types ◽  
Cardiac Cells ◽  
Cardiac Muscle Cells ◽  
Significant Stimulation ◽  
Chick Heart ◽  
Embryonic Chick Heart ◽  
Stimulation Of

The effects of acute exposure to insulin on protein synthesis were examined in primary, differentiated cultures of embryonic chick heart and skeletal muscle cells. Synthetic rates were calculated using the specific activity of tRNA-bound leucine as precursor, a specific activity that was significantly less than that of extracellular leucine but greater than that of free, intracellular leucine at 0.2 mM external leucine. Insulin did not alter these relationships. Doses of insulin in the physiological range produced significant stimulation of protein synthesis in both cell types. Maximal responses, involving approximately 30% increases in both absolute and fractional rates, were observed at higher insulin concentrations. Significant stimulation by insulin was seen in cardiac cells after only 1 h of insulin treatment, and the effects of the hormone were observed both in the presence and absence of serum in the culture medium.

scholarly journals The mode of action of Shiga toxin on peptide elongation of eukaryotic protein synthesis

1987 ◽  
Vol 244 (2) ◽  
pp. 287-294 ◽  
Author(s):  
T G Obrig ◽  
T P Moran ◽  
J E Brown
Keyword(s):  
Protein Synthesis ◽  
Complex Formation ◽  
Shiga Toxin ◽  
Mode Of Action ◽  
Elongation Factor ◽  
Shigella Dysenteriae ◽  
Gtpase Activity ◽  
Elongation Factor 2 ◽  
Peptide Elongation ◽  
Elongation Factor 1

The effect of Shiga toxin, from Shigella dysenteriae 1, on the component reactions of peptide elongation were investigated. Enzymic binding of [3H]phenylalanine-tRNA to reticulocyte ribosomes was inhibited by 50% at 7 nM toxin. Elongation factor 1 (eEF-1)-dependent GTPase activity was also inhibited. Both reactions were not restored by addition of excess eEF-1 protein. In contrast, toxin concentrations of 200 nM were required to inhibit by 50% the elongation factor 2 (eEF-2)-dependent translocation of aminoacyl-tRNA on ribosomes. Addition of excess eEF-2 restored translocation activity. The eEF-2-dependent GTPase activity was unaffected at toxin concentrations below 100 nM, and Shiga-toxin concentrations of up to 1,000 nM did not affect either GTP.eEF-2.ribosome complex-formation or peptidyltransferase activity. Thus Shiga toxin closely resembles alpha-sarcin in action, both being primary inhibitors of eEF-1-dependent reactions. In contrast, the 60 S ribosome inactivators ricin and phytolaccin are primary inhibitors of eEF-2-dependent reactions of peptide elongation.

scholarly journals The selective recruitment of mRNA to the ER and an increase in initiation are important for glucose-stimulated proinsulin synthesis in pancreatic β-cells

2005 ◽  
Vol 391 (2) ◽  
pp. 291-300 ◽  
Author(s):  
Isabel C. Greenman ◽  
Edith Gomez ◽  
Claire E. J. Moore ◽  
Terence P. Herbert
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Regulatory Mechanism ◽  
De Novo ◽  
Secretory Protein ◽  
Secretory Proteins ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Large Pool ◽  
Proinsulin Synthesis

Glucose acutely stimulates proinsulin synthesis in pancreatic β-cells through a poorly understood post-transcriptional mechanism. In the present study, we demonstrate in pancreatic β-cells that glucose stimulates the recruitment of ribosome-associated proinsulin mRNA, located in the cytoplasm, to the ER (endoplasmic reticulum), the site of proinsulin synthesis, and that this plays an important role in glucose-stimulated proinsulin synthesis. Interestingly, glucose has greater stimulatory effect on the recruitment of proinsulin mRNA to the ER compared with other mRNAs encoding secretory proteins. This, as far as we are aware, is the first example whereby mRNAs encoding secretory proteins are selectively recruited to the ER and provides a novel regulatory mechanism for secretory protein synthesis. Contrary to previous reports, and importantly in understanding the mechanism by which glucose stimulates proinsulin synthesis, we demonstrate that there is no large pool of ‘free’ proinsulin mRNA in the cytoplasm and that glucose does not increase the rate of de novo initiation on the proinsulin mRNA. However, we show that glucose does stimulate the rate of ribosome recruitment on to ribosome-associated proinsulin mRNA. In conclusion, our results provide evidence that the selective recruitment of proinsulin mRNA to the ER, together with increases in the rate of initiation are important mediators of glucose-stimulated proinsulin synthesis in pancreatic β-cells.

scholarly journals Effects of chromium picolinate on in vitro lipogenesis and lipolysis in adipose tissue and protein synthesis in liver tissue of pigs

1998 ◽  
Vol 11 (4) ◽  
pp. 428-433 ◽  
Author(s):  
Y. J. Choi ◽  
H. G. Kim ◽  
J. S. Cho ◽  
I. B. Chung ◽  
Y. H. Kim ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Adipose Tissue ◽  
Liver Tissue ◽  
Chromium Picolinate

scholarly journals Inhibition of Protein Synthesis by TOR Inactivation Revealed a Conserved Regulatory Mechanism of the BiP Chaperone in Chlamydomonas

2011 ◽  
Vol 157 (2) ◽  
pp. 730-741 ◽  
Author(s):  
Sandra Díaz-Troya ◽  
María Esther Pérez-Pérez ◽  
Marta Pérez-Martín ◽  
Suzette Moes ◽  
Paul Jeno ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Regulatory Mechanism ◽  
Inhibition Of Protein Synthesis

scholarly journals T-box-mediated control of the anabolic proline biosynthetic genes of Bacillus subtilis

Microbiology ◽  
2011 ◽  
Vol 157 (4) ◽  
pp. 977-987 ◽  
Author(s):  
Jeanette Brill ◽  
Tamara Hoffmann ◽  
Harald Putzer ◽  
Erhard Bremer
Keyword(s):  
Protein Synthesis ◽  
Bacillus Subtilis ◽  
Northern Blot Analysis ◽  
Regulatory Mechanism ◽  
Full Length ◽  
Reporter Strain ◽  
Genetic Studies ◽  
T Box ◽  
Extension Analysis ◽  
Specific Control

Bacillus subtilis possesses interlinked routes for the synthesis of proline. The ProJ–ProA–ProH route is responsible for the production of proline as an osmoprotectant, and the ProB–ProA–ProI route provides proline for protein synthesis. We show here that the transcription of the anabolic proBA and proI genes is controlled in response to proline limitation via a T-box-mediated termination/antitermination regulatory mechanism, a tRNA-responsive riboswitch. Primer extension analysis revealed mRNA leader transcripts of 270 and 269 nt for the proBA and proI genes, respectively, both of which are synthesized from SigA-type promoters. These leader transcripts are predicted to fold into two mutually exclusive secondary mRNA structures, forming either a terminator or an antiterminator configuration. Northern blot analysis allowed the detection of both the leader and the full-length proBA and proI transcripts. Assessment of the level of the proBA transcripts revealed that the amount of the full-length mRNA species strongly increased in proline-starved cultures. Genetic studies with a proB–treA operon fusion reporter strain demonstrated that proBA transcription is sensitively tied to proline availability and is derepressed as soon as cellular starvation for proline sets in. Both the proBA and the proI leader sequences contain a CCU proline-specific specifier codon prone to interact with the corresponding uncharged proline-specific tRNA. By replacing the CCU proline specifier codon in the proBA T-box leader with UUC, a codon recognized by a Phe-specific tRNA, we were able to synthetically re-engineer the proline-specific control of proBA transcription to a control that was responsive to starvation for phenylalanine.

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