[32] Transport of branched-chain amino acids and their corresponding 2-keto acids by mammalian cells

1988 ◽  
pp. 252-260 ◽  
Author(s):  
Michael S. Kilberg ◽  
Mary E. Handlogten
Keyword(s):  
Amino Acids ◽  
Mammalian Cells ◽  
Branched Chain Amino Acids ◽  
Keto Acids ◽  
Branched Chain

scholarly journals Homeostasis of branched-chain amino acids is critical for the activity of TOR signaling in Arabidopsis

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Pengfei Cao ◽  
Sang-Jin Kim ◽  
Anqi Xing ◽  
Craig A Schenck ◽  
Lu Liu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Mammalian Cells ◽  
Branched Chain Amino Acids ◽  
Nutrient Sensing ◽  
Tor Signaling ◽  
Functional Connection ◽  
Primary Input ◽  
Tor Kinase ◽  
Arabidopsis Mutant ◽  
Branched Chain

The target of rapamycin (TOR) kinase is an evolutionarily conserved hub of nutrient sensing and metabolic signaling. In plants, a functional connection of TOR activation with glucose availability was demonstrated, while it is yet unclear whether branched-chain amino acids (BCAAs) are a primary input of TOR signaling as they are in yeast and mammalian cells. Here, we report on the characterization of an Arabidopsis mutant over-accumulating BCAAs. Through chemical interventions targeting TOR and by examining mutants of BCAA biosynthesis and TOR signaling, we found that BCAA over-accumulation leads to up-regulation of TOR activity, which causes reorganization of the actin cytoskeleton and actin-associated endomembranes. Finally, we show that activation of TOR is concomitant with alteration of cell expansion, proliferation and specialized metabolism, leading to pleiotropic effects on plant growth and development. These results demonstrate that BCAAs contribute to plant TOR activation and reveal previously uncharted downstream subcellular processes of TOR signaling.

Influence of branched-chain amino acids and branched-chain keto acids on protein synthesis in isolated hepatocytes

Hepatology ◽  
1987 ◽  
Vol 7 (2) ◽  
pp. 324-329 ◽  
Author(s):  
Wolfgang Base ◽  
Carl Barsigian ◽  
Alisa Schaeffer ◽  
Ellen Shaw ◽  
Jose Martinez ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Isolated Hepatocytes ◽  
Branched Chain Amino Acids ◽  
Keto Acids ◽  
Branched Chain ◽  
Branched Chain Keto Acids

Transamination of branched-chain keto acids by isolated perfused rat kidney.

1978 ◽  
Vol 235 (1) ◽  
pp. E47
Author(s):  
W E Mitch ◽  
W Chan
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Branched Chain Amino Acid ◽  
Keto Acids ◽  
Perfused Rat Kidney ◽  
Branched Chain ◽  
Branched Chain Keto Acids ◽  
Isolated Rat

Isolated rat kidney perfused without substrate released serine, glycine, and taurine, and substantially smaller amounts of other amino acids. When branched-chain keto acids were added, the corresponding amino acids were released at rates amounting to 15-25% of keto acid disappearance. Perfusion with 2 mM alpha-keto-isovalerate or alpha-keto-beta-methylvalerate caused an increased glucose release amounting to 18-23% of keto acid disappearance. The activity of branched-chain amino acid transferase (BATase) was significantly stimulated by perfusion with the analogue of leucine, but not by perfusion with alpha-ketoglutarate, the analogues of valine or isoleucine, or with leucine itself. These findings document that the kidney converts branched-chain keto acids in part to the corresponding amino acids and suggest that the keto analogue of leucine may be involved in the control of renal BATase activity, thereby indirectly regulating the metabolism of branched-chain amino acids.

scholarly journals In Vitro Transcriptional Studies of thebkd Operon of Pseudomonas putida:l-Branched-Chain Amino Acids and d-Leucine Are the Inducers

1999 ◽  
Vol 181 (9) ◽  
pp. 2889-2894 ◽  
Author(s):  
Kunapuli T. Madhusudhan ◽  
Jinhe Luo ◽  
John R. Sokatch
Keyword(s):  
Amino Acids ◽  
Transcriptional Activation ◽  
In Vitro Transcription ◽  
Branched Chain Amino Acids ◽  
Multienzyme Complex ◽  
Keto Acids ◽  
Transcription In Vitro ◽  
Branched Chain ◽  
Hydroxyl Radical Footprinting

ABSTRACT BkdR is the transcriptional activator of the bkdoperon, which encodes the four proteins of the branched-chain keto acid dehydrogenase multienzyme complex of Pseudomonas putida. In this study, hydroxyl radical footprinting revealed that BkdR bound to only one face of DNA over the same region identified in DNase I protection assays. Deletions of even a few bases in the 5′ region of the BkdR-binding site greatly reduced transcription, confirming that the entire protected region is necessary for transcription. In vitro transcription of the bkd operon was obtained by using a vector containing the bkdR-bkdA1 intergenic region plus the putative ρ-independent terminator of the bkdoperon. Substrate DNA, BkdR, and any of thel-branched-chain amino acids or d-leucine was required for transcription. Branched-chain keto acids,d-valine, and d-isoleucine did not promote transcription. Therefore, the l-branched-chain amino acids and d-leucine are the inducers of the bkdoperon. The concentration of l-valine required for half-maximal transcription was 2.8 mM, which is similar to that needed to cause half-maximal proteolysis due to a conformational change in BkdR. A model for transcriptional activation of the bkdoperon by BkdR during enzyme induction which incorporates these results is presented.

BLOOD BRANCHED-CHAIN AMINO AND α-KETO ACID CONCENTRATIONS AND NET EXCHANGE ACROSS THE PORTAL-DRAINED VISCERA AND HINDLIMB OF FED AND FASTED RUMINANTS

1987 ◽  
Vol 67 (4) ◽  
pp. 1011-1020 ◽  
Author(s):  
RICHARD J. EARLY ◽  
JAMES R. THOMPSON ◽  
ROBERT J. CHRISTOPHERSON ◽  
GARY W. SEDGWICK
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Hind Limb ◽  
Venous Blood ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Branched Chain Amino Acid ◽  
Keto Acids ◽  
Branched Chain ◽  
Cattle And Sheep

In the first of two experiments, whole blood branched-chain amino acid (BCAA) and plasma branched-chain α-keto acid (BCKA) concentrations in jugular venous blood were determined in cattle and sheep before and during a 6-d fast. In cattle, concentrations of valine, isoleucine, α-ketoisovalerate (KIV) and α-ketomethylvalerate (KMV) remained unchanged whereas leucine and α-ketoisocaproate (KTC) increased (P < 0.05) during fasting. In sheep, only KIV and KMV remained unchanged whereas BCAA and KIC increased (P < 0.05) during fasting. In a second experiment on cattle chronically catheterized to measure BCAA and BCKA exchange across the portal-drained viscera (PDV) and hindlimb (HL), the PDV added and the HL removed BCAA from the blood of fed cattle. The opposite exchange occurred after a 6-d fast. Releases of BCKA from the PDV and HL in both fed and fasted states were small compared to BCAA exchanges. The data suggest that blood BCAA but not BCKA concentrations may respond differently to starvation in sheep versus cattle and that in cattle the PDV and HL do not release appreciable amounts of BCKA relative to the net movements of the BCAA. Key words: Portal-drained viscera, hind limb, branched-chain amino acids, branched-chain α-keto acids, fasting, ruminants

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