scholarly journals The Intracellular Amino Acid Concentrations Required for Protein Synthesis in Cultured Human Cells

1961 ◽  
Vol 236 (7) ◽  
pp. 2039-2042 ◽  
Author(s):  
Harry Eagle ◽  
Karl A. Piez ◽  
Mina Levy
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Human Cells ◽  
Intracellular Amino Acid ◽  
Cultured Human Cells ◽  
Amino Acid Concentrations

Cell density affects prolidase and prolinase activity and intracellular amino acid levels in cultured human cells

1985 ◽  
Vol 150 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Isaac Myara ◽  
Christiane Charpentier ◽  
Marthe Gautier ◽  
Alain Lemonnier
Keyword(s):  
Amino Acid ◽  
Cell Density ◽  
Human Cells ◽  
Intracellular Amino Acid ◽  
Cultured Human Cells ◽  
Amino Acid Levels

scholarly journals Intracellular amino acid concentrations in children with chronic renal insufficiency

1996 ◽  
Vol 10 (1) ◽  
pp. 46-50 ◽  
Author(s):  
Joana E. Kist-van Holthe tot Echten ◽  
Jan G. M. Huijmans ◽  
Wim C. J. Hop ◽  
Leo A. H. Monnens ◽  
Maria C. J. W. de Jong ◽  
...  
Keyword(s):  
Amino Acid ◽  
Renal Insufficiency ◽  
Chronic Renal Insufficiency ◽  
Intracellular Amino Acid ◽  
Amino Acid Concentrations

Leucine and mTORC1: a complex relationship

2012 ◽  
Vol 302 (11) ◽  
pp. E1329-E1342 ◽  
Author(s):  
Kayleigh M. Dodd ◽  
Andrew R. Tee
Keyword(s):  
Signal Transduction ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Turnover ◽  
Muscle Growth ◽  
Protein Translation ◽  
Amino Acid Availability ◽  
Intracellular Amino Acid ◽  
System L ◽  
Mtorc1 Signaling

Amino acid availability is a rate-limiting factor in the regulation of protein synthesis. When amino acid supplies become restricted, mammalian cells employ homeostatic mechanisms to rapidly inhibit processes such as protein synthesis, which demands high levels of amino acids. Muscle cells in particular are subject to high protein turnover rates to maintain amino acid homeostasis. Mammalian target of rapamycin complex 1 (mTORC1) is an evolutionary conserved multiprotein complex that coordinates a network of signaling cascades and functions as a key mediator of protein translation, gene transcription, and autophagy. Signal transduction through mTORC1, which is centrally involved in muscle growth through enhanced protein translation, is governed by intracellular amino acid supply. The branched-chain amino acid leucine is critical for muscle growth and acts in part through activation of mTORC1. Recent research has revealed that mTORC1 signaling is coordinated primarily at the lysosomal membranes. This discovery has sparked a wealth of research in this field, revealing several different signaling molecules involved in transducing the amino acid signal to mTORC1, including the Rag GTPases, MAP4K3, and Vps34/ULK1. This review evaluates the current knowledge regarding cellular mechanisms that control and sense the intracellular amino acid pool. We discuss the role of leucine and mTORC1 in the regulation of amino acid transport via the system L and system A transporters such as LAT1 and SNAT2, as well as protein degradation via autophagic and proteasomal pathways. We also describe the complexities of energy homeostasis via AMPK and cell receptor-mediated growth signals that also converge on mTORC1. Leucine is a particularly potent regulator of protein turnover, to the extent where leucine stimulation alone is sufficient to stimulate mTORC1 signal transduction. The significance of leucine in this context is not yet known; however, recent advancements in this area will also be covered within this review.

Transmembrane transport and intracellular kinetics of amino acids in human skeletal muscle

1995 ◽  
Vol 268 (1) ◽  
pp. E75-E84 ◽  
Author(s):  
G. Biolo ◽  
R. Y. Fleming ◽  
S. P. Maggi ◽  
R. R. Wolfe
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Human Skeletal Muscle ◽  
De Novo ◽  
Transmembrane Transport ◽  
Acid Transport ◽  
De Novo Synthesis ◽  
Intracellular Amino Acid

We have used stable isotopic tracers of amino acids to measure in vivo transmembrane transport of phenylalanine, leucine, lysine, alanine, and glutamine as well as the rates of intracellular amino acid appearance from proteolysis, de novo synthesis, and disappearance to protein synthesis in human skeletal muscle. Calculations were based on data obtained by the arteriovenous catheterization of the femoral vessels and muscle biopsy. We found that the fractional contribution of transport from the bloodstream to the total intracellular amino acid appearance depends on the individual amino acid, varying between 0.63 +/- 0.02 for phenylalanine and 0.22 +/- 0.02 for alanine. Rates of alanine and glutamine de novo synthesis were approximately eight and five times their rate of appearance from protein breakdown, respectively. The model-derived rate of protein synthesis was highly correlated with the same value calculated by means of the tracer incorporation technique. Furthermore, amino acid transport rates were in the range expected from literature values. Consequently, we conclude that our new model provides a valid means of quantifying the important aspects of protein synthesis, breakdown, and amino acid transport in human subjects.

Regulation of protein synthesis in lung by amino acids and insulin

1983 ◽  
Vol 245 (5) ◽  
pp. E508-E514
Author(s):  
J. M. Besterman ◽  
C. A. Watkins ◽  
D. E. Rannels
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Rat Plasma ◽  
Colloid Osmotic Pressure ◽  
Atp Depletion ◽  
Concentration Addition ◽  
Amino Acid Availability ◽  
Amino Acid Concentrations

Acute effects of amino acid availability and insulin on protein synthesis were investigated in rat lungs perfused in situ with buffer containing either 4.5% fraction V bovine serum albumin (FrV BSA), 4.5% essentially fatty acid-free (FAF) BSA, or 4.5% dextran to maintain colloid osmotic pressure. In the presence of FrV BSA, protein synthesis was unaffected by perfusion for 1 or 3 h with buffer containing no added amino acids (0X), as compared with amino acids at concentrations one (1X) or five (5X) times those in rat plasma. Regardless of the amino acid concentration, addition of insulin was without effect. Likewise, in lungs perfused for 1 h with either FAF BSA or dextran, protein synthesis was insensitive to amino acid availability or to insulin. After 3 h, however, protein synthesis decreased 34 and 37%, respectively, when these lungs were perfused in the absence of both amino acids and insulin. In both cases, the inhibition was prevented by addition of insulin to the perfusate; addition of the hormone to perfusate containing 1X amino acids or elevating perfusate amino acids to 5X did not affect protein synthesis. The deficit in protein synthesis observed in the absence of both amino acids and insulin was not accompanied by ATP depletion or by lower intracellular concentrations of amino acids. Similarly, the effect of insulin was not associated with a general elevation in intracellular amino acid concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Effects of Salmon Ingestion on Post-Exercise Muscle Protein Synthesis: Exploration of Whole Protein Foods Versus Isolated Nutrients

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 650-650
Author(s):  
Kevin Paulussen ◽  
Amadeo Salvador ◽  
Colleen McKenna ◽  
Susannah Scaroni ◽  
Alexander Ulanov ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Myofibrillar Protein ◽  
Post Exercise ◽  
Exercise Muscle ◽  
Amino Acid Concentrations ◽  
Myofibrillar Protein Synthesis ◽  
Stimulation Of

Abstract Objectives Healthy eating patterns consist of eating whole foods as opposed to single nutrients. The maintenance of skeletal muscle mass is of particular interest to overall health. As such, there is a need to underpin the role of eating nutrients within their natural whole-food matrix versus isolated nutrients on the regulation of postprandial muscle protein synthesis rates. This study assessed the effects of eating salmon, a potential food within a healthy Mediterranean style eating pattern, on the stimulation of post-exercise muscle protein synthesis rates versus eating these same nutrients in isolation in healthy young adults. Methods In a crossover design, 10 recreationally active adults (24 ± 4 y; 5 M, 5 F) performed an acute bout of resistance exercise followed by the ingestion of salmon (SAL) (20.5 g protein and 7.5 g fat) or its matched constituents in the form of crystalline amino acids and fish oil (ISO). Blood and muscle biopsies were collected at rest and after exercise at 2 and 5 h during primed continuous infusions of L-[ring-2H5]phenylalanine for the measurement of myofibrillar protein synthesis and plasma amino acid profiles. Data were analyzed by using a 2-factor (time × condition) repeated-measures ANOVA with Tukey's post hoc test. Results Plasma essential amino acid concentrations increased to a similar extent in both SAL and ISO during the postprandial period (P > 0.05). Likewise, postprandial plasma leucine concentrations did not differ between nutrient condition (P > 0.05). The post-exercise myofibrillar protein synthetic responses were similarly stimulated in both nutrition conditions early (0–2 h; 0.079 ± 0.039%/h (SAL) compared to 0.071 ± 0.078%/h (ISO); P = 0.64) and returned to baseline later (2–5 h; 0.046 ± 0.020%/h (SAL) compared to 0.038 ± 0.025%/h (ISO); P = 0.90). Similarly, there were no differences in the stimulation of myofibrillar protein synthesis rates between SAL and ISO during the entire 0–5 h recovery period (0.058 ± 0.024%/h compared to 0.045 ± 0.027%/h, respectively; P = 0.66). Conclusions We show that the ingestion of salmon or its isolated nutrients increases plasma amino acid concentrations and enhances the stimulation of post-exercise muscle protein synthesis rates with no differences in the temporal or cumulative responses in healthy young adults. Funding Sources USDA National Institute of Food and Agriculture Hatch project.

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