scholarly journals Incompatibility of chemical protein synthesis inhibitors with accurate measurement of extended protein degradation rates

2017 ◽  
Vol 5 (5) ◽  
pp. e00359 ◽  
Author(s):  
Christina Chan ◽  
Philip Martin ◽  
Neill J. Liptrott ◽  
Marco Siccardi ◽  
Lisa Almond ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Synthesis Inhibitors ◽  
Degradation Rates ◽  
Chemical Protein Synthesis

scholarly journals The effect of insulin and intermittent mechanical stretching on rates of protein synthesis and degradation in isolated rabbit muscle

1985 ◽  
Vol 230 (1) ◽  
pp. 117-123 ◽  
Author(s):  
R M Palmer ◽  
P A Bain ◽  
P J Reeds
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Suppressive Effect ◽  
Rabbit Muscle ◽  
Degradation Rates ◽  
Forelimb Muscles ◽  
Amino Acid Balance ◽  
Mechanical Stretching ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Tyrosine balance and protein synthesis were studied during the same incubation in isolated rabbit forelimb muscles. From these measurements, protein degradation was calculated. Isolated muscles were usually in a state of negative amino acid balance, principally as a result of the 75% decrease in protein synthesis. Muscles from rabbits starved for 18 h had lower rates of both protein synthesis and degradation compared with muscles from normally fed rabbits. Intermittent mechanical stretching and the addition of insulin at 100 microunits/ml increased rates of both protein synthesis and degradation. Increases in the rate of protein synthesis were proportionately greater in the muscles from starved animals. In muscles from both fed and starved donors, increases in protein-synthesis rates owing to intermittent stretching and insulin were proportionately greater than the increases in degradation rates. For example, insulin increased the rate of protein synthesis in the muscles from starved donors by 111% and the rate of degradation by 31%. Insulin also increased the rate of protein synthesis when added at a higher concentration (100 munits/ml); at this concentration, however, the rate of protein degradation was not increased. The suppressive effect of insulin on high rates of protein degradation in other skeletal-muscle preparations may reflect a non-physiological action of the hormone.

scholarly journals Effect of hypophysectomy on the rates of protein synthesis and degradation in rat liver

1979 ◽  
Vol 178 (3) ◽  
pp. 725-731 ◽  
Author(s):  
R D Conde
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Rat Liver ◽  
Protein Metabolism ◽  
Plasma Proteins ◽  
Degradation Rates ◽  
Hypophysectomized Rats ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The effect of hypophysectomy on the protein metabolism of the liver in vivo was studied. Fractional rates of protein synthesis and degradation were determined in the livers of normal and hypophysectomized rats. Synthesis was measured after the injection of massive amounts of radioactive leucine. Degradation was estimated either as the balance between synthesis and accumulation of stable liver proteins or from the disappearance of radioactivity from the proteins previously labelled by the injection of NaH14CO3. The results indicate that: (1) hypophysectomy diminishes the capacity of the liver to synthesize proteins in vivo, mainly of those that are exported as plasma proteins; (2) livers of both normal and hypophysectomized rats show identical protein-degradation rates, whereas plasma proteins are degraded slowly after hypophysectomy.

scholarly journals Rates of protein turnover in vivo and in vitro in ventricular muscle of hearts from fed and starved rats

1984 ◽  
Vol 222 (2) ◽  
pp. 395-400 ◽  
Author(s):  
V R Preedy ◽  
D M Smith ◽  
N F Kearney ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Ventricular Muscle ◽  
Degradation Rates ◽  
Perfused Hearts

Starvation of 300 g rats for 3 days decreased ventricular-muscle total protein content and total RNA content by 15 and 22% respectively. Loss of body weight was about 15%. In glucose-perfused working rat hearts in vitro, 3 days of starvation inhibited rates of protein synthesis in ventricles by about 40-50% compared with fed controls. Although the RNA/protein ratio was decreased by about 10%, the major effect of starvation was to decrease the efficiency of protein synthesis (rate of protein synthesis relative to RNA). Insulin stimulated protein synthesis in ventricles of perfused hearts from fed rats by increasing the efficiency of protein synthesis. In vivo, protein-synthesis rates and efficiencies in ventricles from 3-day-starved rats were decreased by about 40% compared with fed controls. Protein-synthesis rates and efficiencies in ventricles from fed rats in vivo were similar to values in vitro when insulin was present in perfusates. In vivo, starvation increased the rate of protein degradation, but decreased it in the glucose-perfused heart in vitro. This contradiction can be rationalized when the effects of insulin are considered. Rates of protein degradation are similar in hearts of fed animals in vivo and in glucose/insulin-perfused hearts. Degradation rates are similar in hearts of starved animals in vivo and in hearts perfused with glucose alone. We conclude that the rates of protein turnover in the anterogradely perfused rat heart in vitro closely approximate to the rates in vivo in absolute terms, and that the effects of starvation in vivo are mirrored in vitro.

scholarly journals Effect of corticosterone treatment on muscle protein turnover in adrenalectomized rats and diabetic rats maintained on insulin

1982 ◽  
Vol 204 (3) ◽  
pp. 663-672 ◽  
Author(s):  
Bhanu R. Odedra ◽  
David J. Millward
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Muscle Wasting ◽  
Muscle Protein ◽  
Diabetic Rats ◽  
Constant Infusion ◽  
Degradation Rates ◽  
Adrenalectomized Rats

The effect of corticosterone on protein turnover in skeletal muscle was investigated in growing rats. Protein synthesis was measured in vivo by the constant infusion of [14C]tyrosine. The extent to which any effect of corticosterone is modulated by the hyperinsulinaemia induced by steroid treatment was examined by giving the hormone not only to adrenalectomized rats but also to streptozotocin-induced diabetic rats maintained throughout the treatment period on two dosages of insulin by an implanted osmotic minipump. Approximate rates of protein degradation were also estimated in some cases as the difference between synthesis and net change in muscle protein mass. Measurements were also made of free 3-methylhistidine concentration in muscle and plasma. At 10mg of corticosterone/100g body wt. per day, growth stopped and muscle wasting occurred, whereas at 5 mg of corticosterone/100g body wt. per day no net loss of protein occurred. However, this low dose did induce muscle wasting when insulin concentration was regulated by a dose of 1.2 units/day. Protein synthesis was markedly depressed in all treated groups, the depression in the insulin-maintained rats being marginally more than in the hyperinsulinaemic adrenalectomized rats. The oxidative soleus muscle appeared to be less susceptible to the effect of the corticosterone than was the more glycolytic plantaris or gastrocnemius muscle. Any effect of the corticosterone on protein degradation was much less than its effects on protein synthesis. Where increases in the degradation rates appeared to occur in the rats treated with 10mg of corticosterone/100g body wt. per day, the increases were less than 20%. The free intracellular 3-methylhistidine concentrations were doubled in all groups treated with 5 mg of corticosterone/100g body wt. per day and increased 5-fold in the adrenalectomized rats treated with 10mg of corticosterone/100g body wt. per day, with no change in plasma concentration in any of the groups. It is therefore concluded that: (a) the suppression of protein synthesis is the main effect of glucocorticoids in muscle; (b) marked increases in insulin afford only minor protection against this effect; (c) stimulation of protein degradation may occur, but to a much lesser extent.

scholarly journals Differences in degradation processes for insulin and its receptor in cultured foetal hepatocytes

1983 ◽  
Vol 212 (3) ◽  
pp. 529-537 ◽  
Author(s):  
E Pringault ◽  
C Plas
Keyword(s):  
Protein Synthesis ◽  
Insulin Receptors ◽  
Insulin Binding ◽  
Inhibitory Effect ◽  
Insulin Degradation ◽  
Protein Synthesis Inhibitors ◽  
Degradation Processes ◽  
Degradation Rates ◽  
Number Of Binding Sites ◽  
The Stability

Binding and degradation of 125I-labelled insulin were studied in cultured foetal hepatocytes after exposure to the protein-synthesis inhibitors tunicamycin and cycloheximide. Tunicamycin (1 microgram/ml) induced a steady decrease of insulin binding, which was decreased by 50% after 13 h. As the total number of binding sites per hepatocyte was 20000, the rate of the receptor degradation could not exceed 13 sites/min per hepatocyte. Cycloheximide (2.8 micrograms/ml) increased insulin binding by 30% within 6 h, an effect that persisted for up to 25 h. This drug had a specific inhibitory effect on the degradation of proteins prelabelled for 10 h with [14C]glucosamine, without affecting the degradation of total proteins. Chronic exposure to 10 nM-insulin neither decreased insulin binding nor modified the effect of the drugs. The absence of down-regulation of insulin receptors cannot be attributed to rapid receptor biosynthesis in foetal hepatocytes. Cellular insulin degradation, which is exclusively receptor-mediated, was determined by two different parameters. First, the rate of release of degraded insulin into the medium was 600 molecules/min per hepatocyte with 1 nM labelled hormone, and increased (preincubation with cycloheximide) or decreased (tunicamycin) as a function of the amount of cell-bound insulin. Secondly, the percentage of cell-bound insulin degraded was not changed by the presence of protein-synthesis inhibitors (25-30%). The stability of insulin degradation suggested that this process was dependent on long-life proteinase systems. Such differences in degradation rates and cycloheximide sensitivity imply that hormone- and receptor-degradation processes utilize distinct pathways.

scholarly journals Universality and non-universality of the growth law

2021 ◽  
Author(s):  
Qirun Wang ◽  
Jie Lin
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Ribosomal Proteins ◽  
Correlation Coefficients ◽  
Growth Conditions ◽  
Proliferating Cells ◽  
Translation Speed ◽  
Nutrient Quality ◽  
Degradation Rates ◽  
Mass Fractions

An approximately linear relationship between the fraction of ribosomal proteins in the proteome (ϕR) and the growth rate (μ) holds in proliferating cells when the nutrient quality changes, often referred to as a growth law. While a simple model assuming a constant translation speed of ribosomes without protein degradation can rationalize this growth law, real protein synthesis processes are more complex. This work proposes a general theoretical framework of protein synthesis, taking account of heterogeneous translation speeds among proteins and finite protein degradation. We introduce ribosome allocations as the fraction of active ribosomes producing certain proteins, with two correlation coefficients respectively quantifying the correlation between translation speeds and ribosome allocations, and between protein degradation rates and mass fractions. We prove that the growth law curve generally follows ϕR = (μ + c1)/(c2μ + c3) where c1, c2, and c3 are constants depending on the above correlation coefficients and the translation speed of ribosomal proteins. Our theoretical predictions of ϕR agree with existing data of Saccharomyces cerevisiae. We demonstrate that when different environments share similar correlation coefficients, the growth law curve is universal and up-bent relative to a linear line in slow-growth conditions, which appears valid for Escherichia coli. However, the growth law curve is non-universal and environmental-specific when the environments have significantly different correlation coefficients. Our theories allow us to estimate the translation speeds of ribosomal and non-ribosomal proteins based on the experimental growth law curves.

scholarly journals Defects in autophagy lead to selective in vivo changes in turnover of cytosolic and organelle proteins in Arabidopsis

2021 ◽  
Author(s):  
Lei Li ◽  
Chun Pong Lee ◽  
Akila Wijerathna-Yapa ◽  
Martyna Broda ◽  
Marisa S. Otegui ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Degradation Rate ◽  
T Complex ◽  
Autophagy Induction ◽  
Degradation Rates ◽  
Specific Proteins ◽  
Protein Degradation Rate ◽  
Synthesis And Degradation

AbstractIdentification of autophagic protein cargo in plants by their abundance in autophagy related genes (ATG) mutants is complicated by changes in both protein synthesis and protein degradation. To detect autophagic cargo, we measured protein degradation rate in shoots and roots of Arabidopsis atg5 and atg11 mutant plants. These data show that less than a quarter of proteins changing in abundance are probable cargo and revealed roles of ATG11 and ATG5 in degradation of specific cytosol, chloroplast and ER-resident proteins, and a specialized role for ATG11 in degradation of proteins from mitochondria and chloroplasts. Our data support a role for autophagy in degrading glycolytic enzymes and the chaperonin containing T-complex polypeptide-1 complex. Autophagy induction by Pi limitation changed metabolic profiles and the protein synthesis and degradation rates of atg5 and atg11 plants. A general decrease in the abundance of amino acids and increase in several secondary metabolites in autophagy mutants was consistent with altered catabolism and changes in energy conversion caused by reduced degradation rate of specific proteins. Combining measures of changes in protein abundance and degradation rates, we also identify ATG11 and ATG5 associated protein cargo of low Pi induced autophagy in chloroplasts and ER-resident proteins involved in secondary metabolism.Single Sentence SummaryProtein cargo of autophagy in plants can be discovered by identifying proteins that increase in abundance and decrease in degradation rate in mutants deficient in autophagy machinery

scholarly journals Yeast Cycloheximide-resistant crl Mutants Are Proteasome Mutants Defective in Protein Degradation

1997 ◽  
Vol 8 (12) ◽  
pp. 2487-2499 ◽  
Author(s):  
Uwe-M. Gerlinger ◽  
Roland Gückel ◽  
Michael Hoffmann ◽  
Dieter H. Wolf ◽  
Wolfgang Hilt
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Incorrect Response ◽  
26S Proteasome ◽  
Protein Synthesis Inhibitor ◽  
Temperature Sensitive ◽  
Protein Synthesis Inhibitors ◽  
Synthesis Inhibitor ◽  
Partial Restoration ◽  
Proteasomal Genes

In 1988 McCusker and Haber generated a series of mutants which are resistant to the minimum inhibitory concentration of the protein synthesis inhibitor cycloheximide. These cycloheximide-resistant, temperature-sensitive (crl) mutants, in addition, exhibited other pleiotropic phenotypes, e.g., incorrect response to starvation, hypersensitivity against amino acid analogues, and other protein synthesis inhibitors. Temperature sensitivity of one of these mutants, crl3–2, had been found to be suppressed by a mutation, SCL1–1, which resided in an α-type subunit of the 20S proteasome. We cloned the CRL3 gene by complementation and found CRL3 to be identical to theSUG1/CIM3 gene coding for a subunit of the 19S cap complex of the 26S proteasome. Another mutation, crl21, revealed to be allelic with the 20S proteasomal gene PRE3. crl3–2 and crl21 mutant cells show significant defects in proteasome-dependent proteolysis, whereas theSCL1–1 suppressor mutation causes partial restoration of crl3–2-induced proteolytic defects. Notably, cycloheximide resistance was also detected for other proteolytically deficient proteasome mutants (pre1–1,pre2–1, pre3–1, pre4–1). Moreover, proteasomal genes were found within genomic sequences of 9 of 13 chromosomal loci to which crl mutations had been mapped. We therefore assume that most if not all crlmutations reside in the proteasome and that phenotypes found are a result of defective protein degradation.

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