scholarly journals The two mammalian mitochondrial stress proteins, grp 75 and hsp 58, transiently interact with newly synthesized mitochondrial proteins.

1991 ◽  
Vol 2 (2) ◽  
pp. 165-179 ◽  
Author(s):  
L A Mizzen ◽  
A N Kabiling ◽  
W J Welch
Keyword(s):  
Mammalian Cells ◽  
Stress Proteins ◽  
Mitochondrial Proteins ◽  
Amino Acid Analogue ◽  
Hsp 70 ◽  
Protein Maturation ◽  
Mitochondrial Stress ◽  
Chase Period ◽  
Acid Analogue ◽  
Glucose Regulated Protein

In mammalian cells, two of the so-called heat shock (hsp) or stress proteins are components of the mitochondria. One of these, hsp 58, is a member of the bacterial GroEL family, whereas the other, glucose-regulated protein (grp) 75, represents a member of the hsp 70 family of stress proteins. Owing to previous studies implicating a role for both the hsp 70 and GroEL families in facilitating protein maturation events, we used the method of native immunoprecipitation to examine whether hsp 58 and grp 75 might interact with other proteins of the mitochondria. In cells pulse-labeled with [35S]-methionine, a significant number of newly synthesized mitochondrial proteins co-precipitated with either hsp 58 or grp 75. Such interactions appeared transient. For example, providing the pulse-labeled cells a subsequent chase period in the absence of radiolabel resulted in a reduction of co-precipitating proteins. If the pulse-chase labeling experiments were performed in the presence of an amino acid analogue, somewhat different results were obtained. Specifically, although many of the newly synthesized and analogue-containing proteins again were observed to co-precipitate with grp 75, the interactions did not appear transient, but instead were stable. Under steady-state labeling conditions, we also observed a portion of hsp 58 and grp 75 in an apparent complex with one another. On addition of ATP, the complex was dissociated. Accompanying this dissociation was the concomitant autophosphorylation of grp 75. On the basis of these observations, as well as previous studies examining the structure/function of the hsp 70 and GroEL proteins, we suspect that both hsp 58 and grp 75 interact with and facilitate the folding and assembly of proteins as they enter into the mitochondria.

scholarly journals Cellular and biochemical events in mammalian cells during and after recovery from physiological stress.

1986 ◽  
Vol 103 (5) ◽  
pp. 2035-2052 ◽  
Author(s):  
W J Welch ◽  
J P Suhan
Keyword(s):  
Mammalian Cells ◽  
Stress Proteins ◽  
Physiological Stress ◽  
Close Association ◽  
Recovery Period ◽  
Recovery Process ◽  
Acid Analogue ◽  
Double Label ◽  
The Individual ◽  
Cytoplasmic Ribosomes

We have examined and compared a number of cellular and biochemical events associated with the recovery process of rat fibroblasts placed under stress by different agents. Metabolic pulse-labeling studies of cells recovering from either heat-shock treatment, exposure to sodium arsenite, or exposure to an amino acid analogue of proline, L-azetidine 2-carboxylic acid, revealed interesting differences with respect to the individual stress proteins produced, their kinetics of induction, as well as the decay in their synthesis during the recovery period. In the initial periods of recovery, the major stress-induced 72-kD protein accumulates within the altered nucleoli in close association with the pre-ribosomal-containing granular region. During the later times of recovery from stress, the nucleoli begin to regain a normal morphology, show a corresponding loss of the 72-kD protein, and the majority of the protein now begins to accumulate within the cytoplasm in three distinct locales: the perinuclear region, along the perimeter of the cells, and finally in association with large phase-dense structures. These latter structures appear to consist of large aggregates of phase-dense material with no obvious encapsulating membrane. More interestingly we show, using double-label indirect immunofluorescence analysis, that much of the perinuclear and cell perimeter-distributed 72-kD protein coincides with the distribution of the cytoplasmic ribosomes. We discuss the possible implications of the presence of the 72-kD stress proteins within the pre-ribosomal-containing granular region of the nucleolus as well as its subsequent colocalization with cytoplasmic ribosomes in terms of the translational changes which occur in cells both during and after recovery from physiological stress.

scholarly journals Lipid disequilibrium disrupts ER proteostasis by impairing ERAD substrate glycan trimming and dislocation

2017 ◽  
Vol 28 (2) ◽  
pp. 270-284 ◽  
Author(s):  
Milton To ◽  
Clark W. H. Peterson ◽  
Melissa A. Roberts ◽  
Jessica L. Counihan ◽  
Tiffany T. Wu ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Mammalian Cells ◽  
26S Proteasome ◽  
Unfolded Protein ◽  
Acid Analogue ◽  
Triacsin C ◽  
Chain Acyl ◽  
Dependent Cell ◽  
Outstanding Question ◽  
The Unfolded Protein Response

The endoplasmic reticulum (ER) mediates the folding, maturation, and deployment of the secretory proteome. Proteins that fail to achieve their native conformation are retained in the ER and targeted for clearance by ER-associated degradation (ERAD), a sophisticated process that mediates the ubiquitin-dependent delivery of substrates to the 26S proteasome for proteolysis. Recent findings indicate that inhibition of long-chain acyl-CoA synthetases with triacsin C, a fatty acid analogue, impairs lipid droplet (LD) biogenesis and ERAD, suggesting a role for LDs in ERAD. However, whether LDs are involved in the ERAD process remains an outstanding question. Using chemical and genetic approaches to disrupt diacylglycerol acyltransferase (DGAT)–dependent LD biogenesis, we provide evidence that LDs are dispensable for ERAD in mammalian cells. Instead, our results suggest that triacsin C causes global alterations in the cellular lipid landscape that disrupt ER proteostasis by interfering with the glycan trimming and dislocation steps of ERAD. Prolonged triacsin C treatment activates both the IRE1 and PERK branches of the unfolded protein response and ultimately leads to IRE1-dependent cell death. These findings identify an intimate relationship between fatty acid metabolism and ER proteostasis that influences cell viability.

scholarly journals Effects of the Bacterial Extract OM-85 on Phagocyte Functions and the Stress Response

1994 ◽  
Vol 3 (2) ◽  
pp. 143-148 ◽  
Author(s):  
S. Baladi ◽  
S. Kantengwa ◽  
Y. R. A. Donati ◽  
B. S. Polla
Keyword(s):  
Stress Response ◽  
Respiratory Burst ◽  
Stress Proteins ◽  
Human Peripheral Blood ◽  
Stress Protein ◽  
Blood Monocytes ◽  
Bacterial Extract ◽  
Heat Shock Stress ◽  
Intracellular Expression ◽  
Glucose Regulated Protein

The effects of the bacterial extract OM-85 on the respiratory burst, intracellular calcium and the stress response have been investigated in human peripheral blood monocytes from normal donors. Activation of the respiratory burst during bacterial phagocytosis has been previously associated with heat shock/stress proteins synthesis. Whereas OM-85 stimulated superoxide production and increased Ca2+mobilization, it fared to induce synthesis of classical HSPs. The lack of stress protein induction was observed even in the presence of iron which potentiates both oxidative injury and stress protein induction during bacterial phagocytosis. However OM-85 induced a 75–78 kDa protein, which is likely to be a glucose regulated protein (GRP78), and enhanced intracellular expression of interleukin-lβ precursor.

scholarly journals Isolation and characterization of a new class of amino-acid-analogue-resistant mutants inAspergillus nidulansusing reduced carbon flow

1979 ◽  
Vol 34 (2) ◽  
pp. 121-130 ◽  
Author(s):  
Mahavir Singh ◽  
Umakant Sinha
Keyword(s):  
Amino Acid ◽  
Aromatic Amino Acids ◽  
Sole Source ◽  
Amino Acid Analogue ◽  
Linkage Groups ◽  
Isolation And Characterization ◽  
Acid Analogue ◽  
Amino Acid Analogues ◽  
Resistant Mutants ◽  
Growth Requirement

SUMMARYFour recessive amino-acid-analogue-resistant mutants were isolated on a medium containing acetate as the sole carbon source and the amino acid analogues p-fluorophenylalanine and ethionine. None of the mutants showed any growth requirement. Analysis of growth on media containing an amino acid as the sole nitrogen source indicated that two mutants out of the four possess normal systems for utilization of acidic, neutral, basic and aromatic amino acids. The mutantsfpa70 andfpa71 showed reduced growth on tryptophan as the sole source of nitrogen. Three new loci, identified after preliminary genetic analysis, were located on three linkage groups: one each on linkage groups I, VI and VIII.

scholarly journals Growth induced translocation effectively directs an amino acid analogue to developing zones in Agaricus bisporus

2020 ◽  
Vol 124 (12) ◽  
pp. 1013-1023 ◽  
Author(s):  
Koen C. Herman ◽  
Han A.B. Wösten ◽  
Mark D. Fricker ◽  
Robert-Jan Bleichrodt
Keyword(s):  
Amino Acid ◽  
Agaricus Bisporus ◽  
Amino Acid Analogue ◽  
Acid Analogue
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