Autoradiographische Untersuchungen zur Proteinsynthese während der Frühentwicklung von Dermestes frischi (Coleoptera) / Autoradiographic Investigations on Protein Synthesis During Early Development of Dermestes frischi (Coleoptera)

1972 ◽  
Vol 27 (2) ◽  
pp. 193-195 ◽  
Author(s):  
H. W. Küthe
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Early Development ◽  
Free Amino Acids ◽  
Free Amino ◽  
Protein Fractions ◽  
Cleavage Stages ◽  
Cortical Regions

Injection of tritiated phenylalanine or leucine in eggs shortly after deposition shows the importance and use of free amino acids during cleavage stages. First the activity is found homogeneously distributed in the yolk system and ooplasm. In late cleavage stages the amino acids are incorporated into the periplasm of the egg. These results lead to the conclusions, that there is a continuous transfer of material out of the yolk system into cortical regions during cleavage. Secondly the first new synthetized protein fractions are located in the cortical ooplasm.

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.

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 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.

Free amino acids in the early cleavage stages of the rabbit egg

1973 ◽  
Vol 31 (1) ◽  
pp. 38-46 ◽  
Author(s):  
U. Petzoldt ◽  
G. Briel ◽  
G.H.M. Gottschewski ◽  
V. Neuhoff
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Early Cleavage ◽  
Cleavage Stages

scholarly journals Ingestion of Free Amino Acids as Opposed to Intact Protein Increases Amino Acid Absorption but Does Not Further Augment Postprandial Muscle Protein Synthesis Rates

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 673-673
Author(s):  
Michelle E G Weijzen ◽  
Rob JJ van Gassel ◽  
Imre W K Kouw ◽  
Stefan H M Gorissen ◽  
Marcel CG van de Poll ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Digestion ◽  
Acid Absorption ◽  
Amino Acid Absorption

Abstract Objectives The rate of protein digestion and amino acid absorption determines the postprandial rise in circulating amino acids and, as such, modulates postprandial muscle protein synthesis rates. This study compares protein digestion and amino acid absorption kinetics and the subsequent muscle protein synthetic response following ingestion of intact protein versus an equivalent amount of free, crystalline amino acids. Methods Twenty-four healthy, young subjects (age: 22 ± 3 y, BMI: 23 ± 2 kg·m−2, sex: 12 M/12F) ingested 30 g intrinsically L-[1–13C]-phenylalanine and L-[1–13C]-leucine labeled milk protein (PROT; n = 12) or an equivalent amount of free amino acids (AA; n = 12). In addition, subjects received primed continuous L-[ring-2H5]-phenylalanine, L-[ring-3,5–2H2]-tyrosine, and L-[1–13C]-leucine infusions. Blood samples and muscle biopsies were obtained frequently to assess protein digestion and amino acid absorption kinetics and subsequent muscle protein synthesis rates over a 6 h postprandial period. An unpaired t-test was used to compare overall exogenous phenylalanine release in plasma. For other parameters repeated measures ANOVA were applied to determine differences between groups over time (time as within, and group as between-subjects factor). Data are expressed as mean ± SD. Results Postprandial plasma amino acid concentrations and exogenous phenylalanine appearance rates increased after ingestion of PROT and AA (both, P < 0.001), with a greater increase following ingestion of AA when compared to PROT (time*group interaction P < 0.001). Exogenous phenylalanine release in plasma assessed over the 6 h postprandial period, was greater in AA (76 ± 9%) compared with PROT (59 ± 10%; P < 0.001). Ingestion of AA and PROT strongly increased muscle protein synthesis rates based upon L-[ring-2H5]-phenylalanine (time effect P < 0.001), with no differences between groups (from 0.037 ± 0.015 to 0.053 ± 0.014%·h−1 and from 0.039 ± 0.016 to 0.051 ± 0.010%·h−1, respectively; time*group interaction P = 0.629). Conclusions Ingestion of free amino acids as opposed to intact milk protein is followed by more rapid amino acid absorption and greater postprandial plasma amino acid availability, but this does not further augment postprandial muscle protein synthesis rates. Funding Sources This research did not receive external funding.

scholarly journals The mitochondrial pool of free amino acids reflects the composition of mitochondrial DNA-encoded proteins: indication of a post- translational quality control for protein synthesis

2008 ◽  
Vol 28 (5) ◽  
pp. 239-249 ◽  
Author(s):  
Catherine Ross-Inta ◽  
Chern-Yi Tsai ◽  
Cecilia Giulivi
Keyword(s):  
Amino Acids ◽  
Mitochondrial Dna ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Translational Control ◽  
Free Amino Acids ◽  
Free Amino ◽  
Quantitative Information ◽  
Adequate Diet ◽  
Encoded Proteins

Mitochondria can synthesize a limited number of proteins encoded by mtDNA (mitochondrial DNA) by using their own biosynthetic machinery, whereas most of the proteins in mitochondria are imported from the cytosol. It could be hypothesized that the mitochondrial pool of amino acids follows the frequency of amino acids in mtDNA-encoded proteins or, alternatively, that the profile is the result of the participation of amino acids in pathways other than protein synthesis (e.g. haem biosynthesis and aminotransferase reactions). These hypotheses were tested by evaluating the pool of free amino acids and derivatives in highly-coupled purified liver mitochondria obtained from rats fed on a nutritionally adequate diet for growth. Our results indicated that the pool mainly reflects the amino acid composition of mtDNA-encoded proteins, suggesting that there is a post-translational control of protein synthesis. This conclusion was supported by the following findings: (i) correlation between the concentration of free amino acids in the matrix and the frequency of abundance of amino acids in mtDNA-encoded proteins; (ii) the similar ratios of essential-to-non-essential amino acids in mtDNA-encoded proteins and the mitochondrial pool of amino acids; and (iii), lack of a correlation between codon usage or tRNA levels and amino-acid concentrations. Quantitative information on the mammalian mitochondrial content of amino acids, such as that presented in the present study, along with functional studies, will help us to better understand the pathogenesis of mitochondrial diseases or the biochemical implications in mitochondrial metabolism.

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