scholarly journals Regulation of protein synthesis in rat liver cell-free systems by amino acids

1972 ◽  
Vol 31 (3) ◽  
pp. 273-279 ◽  
Author(s):  
M. J. Clemens
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Liver ◽  
Liver Cell

The effect of cell-sap fractions on incorporation of amino acids into protein in rat liver cell-free systems

1970 ◽  
Vol 48 (7) ◽  
pp. 735-739 ◽  
Author(s):  
C. C. Liew ◽  
A. Korner
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Liver ◽  
Liver Cell ◽  
Enzyme Preparation ◽  
Transfer Factors

The ability of rat liver cell sap, pH 5 enzyme preparation, partially purified transfer factors I and II (PTF), and a mixture of the latter two to support protein synthesis in a ribosome system in vitro was compared. Protein synthesis increased as the ratio of pH 5 enzyme to ribosomes and PTF was raised and as the ratio of PTF to pH 5 enzymes and ribosomes was raised. The best ratios of these fractions were not as efficient as unfractionated cell sap at supporting protein synthesis; some factor had been lost or inactivated during fractionation. Incubation with cell sap caused changes in ribosomal profiles leading to less polysomes and more monomeric and dimeric ribosomes but no changes were noted on incubation with pH 5 enzymes and PTF.

scholarly journals Effects of the hepatotoxic agents retrorsine and aflatoxin B1 on hepatic protein synthesis in the rat

1968 ◽  
Vol 109 (1) ◽  
pp. 87-91 ◽  
Author(s):  
S. Villa-Treviño ◽  
D. D. Leaver
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Liver ◽  
Aflatoxin B1 ◽  
Plasma Proteins ◽  
Pyrrolizidine Alkaloid ◽  
Main Site ◽  
Nuclear Rna ◽  
Hepatic Protein Synthesis

1. Aflatoxin and the pyrrolizidine alkaloid retrorsine inhibited the incorporation of labelled amino acids into rat liver and plasma proteins in vivo. Inhibition was greater and detected earlier with retrorsine (1hr.) than with aflatoxin (3hr.). 2. Both toxins affected the liver ribosomal aggregates, causing increases in the proportion of monomers plus dimers. The effect of retrorsine was greater than that of aflatoxin. 3. Incorporation of labelled amino acids into proteins of cell-free preparations of liver from rats treated with aflatoxin was lower than in control preparations. The main site of inhibition appeared to be the ribosomes. 4. Both toxins inhibited the incorporation of orotate into liver nuclear RNA 1hr. after administration.

scholarly journals Inhibitory effect of pH5 enzyme from non-lactating bovine mammary gland on various stages of protein synthesis in the rat liver amino acid-incorporating system

1969 ◽  
Vol 115 (4) ◽  
pp. 671-678 ◽  
Author(s):  
M. D. Herrington ◽  
A. O. Hawtrey
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Inhibitory Effect ◽  
Bovine Mammary Gland ◽  
Free System ◽  
Enzyme Fraction

1. pH5 enzyme from non-lactating bovine mammary gland was found to contain potent inhibitors of protein synthesis in the rat liver cell-free system. These inhibitors affect (a) formation of aminoacyl-tRNA where tRNA represents transfer RNA, (b) transfer of labelled amino acids from rat liver amino[14C]acyl-tRNA to protein in rat liver polyribosomes, and (c) incorporation of 14C-labelled amino acids into peptide by rat liver polyribosomes supplemented with rat liver pH5 enzyme. 2. Increasing amounts of pH5 enzyme from bovine mammary gland progressively inhibited the incorporation of labelled amino acids into protein by a complete incorporating system from rat liver. Approx. 80% inhibition was observed at a concentration of 2mg. of protein of pH5 enzyme from bovine mammary gland. The inhibitory effect of the bovine pH5 enzyme fraction could not be overcome by the addition of increasing amounts of rat liver pH5 enzyme. 3. Fractionation of bovine pH5 enzyme with ammonium sulphate into four fractions showed that all the fractions inhibited the incorporation of 14C-labelled amino acids in the rat liver system, but to varying extents. The highest inhibition observed (90%) was exhibited by the 60%-saturated-ammonium sulphate fraction. 4. Heat treatment of bovine pH5 enzyme at various temperatures caused only a partial loss of its inhibitory effect on labelled amino acid incorporation by the rat liver system. Treatment at 105° for 5min. resulted in the bovine pH5 enzyme fraction losing 30% of its inhibitory activity. 5. pH5 enzyme from bovine mammary gland strongly inhibited the charging of rat liver tRNA in the presence of its own pH5 enzymes. 6. The transfer of labelled amino acids from rat liver amino[14C]acyl-tRNA to protein in a system containing rat liver polyribosomes and pH5 enzyme was almost completely inhibited by bovine pH5 enzyme at a concentration of 2mg. of protein of the enzyme fraction. 7. One of the inhibitors of various stages of protein synthesis in rat liver present in bovine pH5 enzyme was identified as an active ribonuclease, and the second inhibitor present was shown to be tRNA.

scholarly journals The effect of starvation on the rate of protein synthesis in rat liver and small intestine

1979 ◽  
Vol 178 (2) ◽  
pp. 373-379 ◽  
Author(s):  
M A McNurlan ◽  
A M Tomkins ◽  
P J Garlick
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Small Intestine ◽  
Rat Liver ◽  
Specific Radioactivity ◽  
Jejunal Mucosa ◽  
Liver Protein ◽  
Total Liver

1. A method is described that allows for measurement of protein synthesis in liver and intestine in the rat. By injecting a massive amount of [14C]leucine (100 mumol/100 g body wt.) an attempt has been made to over come problems of precursor specific radioactivity and problems arising from the breakdown of labelled protein that are encountered when tracer amounts of amino acids are used. 2. Starvation for 2 days resulted in decline in the rate of total liver protein synthesis from 87%/day to 62%/day. 3. In jejunal mucosa the rate of protein synthesis was 136%/day. This declined to 105%/day after 2 days of starvation.

scholarly journals Incorporation of Amino Acids into Protein in a System Containing Rat Liver Ribonucleoprotein Particles and Chick Liver Cell Sap.

1963 ◽  
Vol 17 ◽  
pp. 866-866
Author(s):  
Alexandra von der Decken ◽  
S. Pedersen ◽  
Lars Gunnar Sillén ◽  
P. H. Nielsen ◽  
Jon Munch-Petersen
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Liver Cell ◽  
Ribonucleoprotein Particles

Protein Synthesis in Rat Liver: Influence of Amino Acids in Diet on Microsomes and Polysomes

Science ◽  
1965 ◽  
Vol 150 (3696) ◽  
pp. 628-629 ◽  
Author(s):  
A. Fleck ◽  
J. Shepherd ◽  
H. N. Munro
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Liver

Activation of the Protein Synthetic Capacity of Rat Liver Cell Sap by Amino-acids

1971 ◽  
Vol 232 (34) ◽  
pp. 252-253 ◽  
Author(s):  
M. J. CLEMENS ◽  
A. KORNER
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Liver Cell ◽  
Synthetic Capacity
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