scholarly journals Compartmentation of free amino acids for protein synthesis in rat liver

1974 ◽  
Vol 140 (3) ◽  
pp. 539-545 ◽  
Author(s):  
Judith Airhart ◽  
Alda Vidrich ◽  
Edward A. Khairallah
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Rat Liver ◽  
Free Amino Acids ◽  
Free Amino ◽  
Protein Biosynthesis ◽  
Specific Radioactivity ◽  
Intracellular Pool ◽  
Intracellular Compartments ◽  
Intracellular Amino Acids

The concept that a general intracellular pool serves as the sole precursor of amino acids for protein biosynthesis has been vigorously debated in recent years. To help resolve this controversy, we followed the distribution of intraperitoneally administered [3H]valine in the tRNA and the extracellular and intracellular compartments of rat liver. The specific radioactivity of the valine released from isolated tRNA was 2–3 times higher than that of intracellular valine, suggesting that the intracellular pool cannot be the sole precursor of amino acids used for charging tRNA. In addition, the specific radioactivity of the tRNA was only half that of the extracellular valine. Therefore it is unlikely that the valyl-tRNA is charged exclusively with amino acids derived from the extracellular pool. A model is proposed which stipulates that both extracellular and intracellular amino acids contribute to a restricted compartment that funnels amino acids towards protein biosynthesis.

scholarly journals The specific radioactivity of the precursor pool for estimates of the rate of protein synthesis (Short Communication)

1973 ◽  
Vol 134 (4) ◽  
pp. 1127-1130 ◽  
Author(s):  
Edward B. Fern ◽  
Peter J. Garlick
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Short Communication ◽  
Specific Radioactivity ◽  
Precursor Pool

Infusion of rats with [U-14C]glycine resulted in labelling of glycine and serine in tissue proteins. The pattern of labelling in protein more nearly resembled that of the free amino acids in the tissue than in the plasma.

scholarly journals Amino acid regulation of synthesis of ribonucleic acid and protein in the liver of rats

1971 ◽  
Vol 124 (2) ◽  
pp. 385-392 ◽  
Author(s):  
R. W. Wannemacher ◽  
C. F. Wannemacher ◽  
M. B. Yatvin
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Cellular Protein ◽  
Deficient Diet ◽  
Cellular Protein Content ◽  
Regulate Protein

Weanling (23-day-old) rats were fed on either a low-protein diet (6% casein) or a diet containing an adequate amount of protein (18% casein) for 28 days. Hepatic cells from animals fed on the deficient diet were characterized by markedly lower concentrations of protein and RNA in all cellular fractions as compared with cells from control rats. The bound rRNA fraction was decreased to the greatest degree, whereas the free ribosomal concentrations were only slightly less than in control animals. A good correlation was observed between the rate of hepatic protein synthesis in vivo and the cellular protein content of the liver. Rates of protein synthesis both in vivo and in vitro were directly correlated with the hepatic concentration of individual free amino acids that are essential for protein synthesis. The decreased protein-synthetic ability of the ribosomes from the liver of protein-deprived rats was related to a decrease in the number of active ribosomes and heavy polyribosomes. The lower ribosomal content of the hepatocytes was correlated with the decreased concentration of essential free amino acids. In the protein-deprived rats, the rate of accumulation of newly synthesized cytoplasmic rRNA was markedly decreased compared with control animals. From these results it was concluded that amino acids regulate protein synthesis (1) by affecting the number of ribosomes that actively synthesize protein and (2) by inhibiting the rate of synthesis of new ribosomes. Both of these processes may involve the synthesis of proteins with a rapid rate of turnover.

Studies on pathogenesis of experimental fatty liver (I) variation in the pattern of free amino acids of albino rat liver

1966 ◽  
Vol 1 (1) ◽  
pp. 38-39
Author(s):  
Y. Takaoka ◽  
K. Yokouchi ◽  
G. Mitsuoka ◽  
H. Tajima ◽  
E. Uchiyama ◽  
...  
Keyword(s):  
Amino Acids ◽  
Fatty Liver ◽  
Rat Liver ◽  
Free Amino Acids ◽  
Free Amino ◽  
Albino Rat

scholarly journals Pinocytosis and intracellular degradation of exogenous protein: modulation by amino acids.

1983 ◽  
Vol 96 (6) ◽  
pp. 1586-1591 ◽  
Author(s):  
J M Besterman ◽  
J A Airhart ◽  
R B Low ◽  
D E Rannels
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Free Amino Acids ◽  
Free Amino ◽  
De Novo ◽  
Serum Proteins ◽  
Fluid Phase ◽  
Cellular Protein ◽  
Intracellular Degradation ◽  
Exogenous Protein

Intracellular degradation of exogenous (serum) proteins provides a source of amino acids for cellular protein synthesis. Pinocytosis serves as the mechanism for delivering exogenous protein to the lysosomes, the major site of intracellular degradation of exogenous protein. To determine whether the availability of extracellular free amino acids altered pinocytic function, we incubated monolayers of pulmonary alveolar macrophages with the fluid-phase marker, [14C]sucrose, and we dissected the pinocytic process by kinetic analysis. Additionally, intracellular degradation of endogenous and exogenous protein was monitored by measuring phenylalanine released from the cell monolayers in the presence of cycloheximide. Results revealed that in response to a subphysiological level of essential amino acids or to amino acid deprivation, (a) the rate of fluid-phase pinocytosis increased in such a manner as to preferentially increase both delivery to and size of an intracellular compartment believed to be the lysosomes, (b) the degradation of exogenously supplied albumin increased, and (c) the fraction of phenylalanine derived from degradation of exogenous albumin and reutilized for de novo protein synthesis increased. Thus, modulation of the pinosome-lysosome pathway may represent a homeostatic mechanism sensitive to the availability of extracellular free amino acids.

scholarly journals Compartmentation of albumin and ferritin synthesis in rat liver in vivo

1976 ◽  
Vol 156 (1) ◽  
pp. 189-192 ◽  
Author(s):  
E B Fern ◽  
P J Garlick
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Free Amino Acids ◽  
Free Amino ◽  
Plasma Albumin ◽  
Ferritin Synthesis ◽  
Liver Ferritin ◽  
Ferritin Synthesis In

Infusion of rats with [U-14C]glycine resulted in labelling of glycine and serine in plasma albumin and liver ferritin. The patterms of labelling in these two proteins were not similar, suggesting that each is synthesized from a different pool of free amino acids.

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 Preparation of polyribosome aminoacyl-transfer ribonucleic acid from the muscle of chick embryos.

1975 ◽  
Vol 147 (3) ◽  
pp. 473-477 ◽  
Author(s):  
M Nwagwu
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Sodium Dodecyl Sulphate ◽  
Ribonucleic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Sodium Dodecyl ◽  
Specific Radioactivity ◽  
Chick Embryos ◽  
Aminoacyl Transfer

A procedure for preparing polyribosome aminoacyl-tRNA free from contamination by supernatant aminoacyl-tRNA and free amino acids is described. Important features of the procedure are the use of acidic buffers to help protect the amino acid-tRNA linkage and the inclusion of sodium dodecyl sulphate, to inhibit ribonuclease activity. The specific radioactivity of polyribosome aminoacyl-tRNA is high within 30s and reaches a maximum in 2 1/2 min, well ahead of polyribosome peptides which, as described by Herrmann et al. (1971), attain maximum specific radioactivity in about 10 min.

Rat liver and kidney pools of free amino acids in norm and with different doses of pyrazinamide

2006 ◽  
Vol 164 ◽  
pp. S95
Author(s):  
Larysa B. Bondarenko ◽  
Natalia A. Saprykina ◽  
Valentina M. Kovalenko
Keyword(s):  
Amino Acids ◽  
Rat Liver ◽  
Free Amino Acids ◽  
Free Amino ◽  
Liver And Kidney ◽  
Different Doses

Intracellular low molecular weight iron

1989 ◽  
Vol 17 (3) ◽  
pp. 490-490 ◽  
Author(s):  
N. DEIGHTON ◽  
R. C. HIDER
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Rat Liver ◽  
Free Amino Acids ◽  
Free Amino ◽  
Low Molecular Weight ◽  
High Affinity ◽  
Chemical Techniques ◽  
Low Molecular Weight Iron

Summary A low molecular weight complex of an iron oligomer (Mr ~ 1000) has been isolated from rat liver and characterized physically and chemically. The h.p.l.c.-purified material contains the free amino acids glutamate and aspartate. Chemical techniques suggest the iron present in the factor is as iron(III) and is readily donated to high-affinity chelators such as the hydroxypyridinones and desferoxamine.

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