scholarly journals Fractional synthesis rates in vivo of skeletal-muscle myosin isoenzymes

1987 ◽  
Vol 245 (1) ◽  
pp. 133-137 ◽  
Author(s):  
P Gregory ◽  
R B Low ◽  
W S Stirewalt
Keyword(s):  
Synthesis Rate ◽  
Single Muscle ◽  
Skeletal Muscle Myosin ◽  
Fast Myosin ◽  
Significant Difference ◽  
Myosin Isoenzymes ◽  
Fractional Synthesis ◽  
Muscle Myosin ◽  
Masseter Muscles

The synthesis rates of different myosin isoenzymes in a single muscle, and of the same isoenzymes in different muscles (soleus, masseter and plantaris), were measured. The rate of total protein synthesis was significantly higher in the soleus [greater than 95% slow myosin (SM)] than in the plantaris [greater than 95% fast myosin (FM)]. Two fast isoenzymes, FM2 and FM3, were synthesized at different rates in the masseter, and SM was synthesized at a faster rate than FM. Intermediate myosin had a synthesis rate similar to that of FM. There was a small but significant difference between the synthesis rates of the SM isoenzymes of the soleus and masseter muscles. FM3 was synthesized faster in the masseter than in the plantaris, whereas FM2 was synthesized faster in the plantaris than in the masseter.

Evidence for increased synthesis of lipoprotein(a) in the nephrotic syndrome.

1998 ◽  
Vol 9 (8) ◽  
pp. 1474-1481
Author(s):  
M G De Sain-Van Der Velden ◽  
D J Reijngoud ◽  
G A Kaysen ◽  
M M Gadellaa ◽  
H Voorbij ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Synthesis Rate ◽  
Fractional Synthesis Rate ◽  
Lipoprotein A ◽  
Control Subjects ◽  
Apolipoprotein A ◽  
Catabolic Rate ◽  
Fractional Synthesis ◽  
The Mean

In patients with the nephrotic syndrome, markedly increased levels of lipoprotein(a) (Lp(a)) concentration have been frequently reported, and it has been suggested that this may contribute to the increased cardiovascular risk in these patients. The mechanism, however, is not clear. In the present study, in vivo fractional synthesis rate of Lp(a) was measured using incorporation of the stable isotope 13C valine. Under steady-state conditions, fractional synthesis rate equals fractional catabolic rate (FCR). FCR of Lp(a) was estimated in five patients with the nephrotic syndrome and compared with five control subjects. The mean plasma Lp(a) concentration in the patients (1749+/-612 mg/L) was higher than in control subjects (553+/-96 mg/L). Two patients were heterozygous for apolipoprotein(a) (range, 19 to 30 kringle IV domains), whereas all control subjects were each homozygous with regard to apolipoprotein(a) phenotype (range, 18 to 28 kringle IV domains). The FCR of Lp(a) was comparable between control subjects (0.072+/-0.032 pools/d) and patients (0.064+/-0.029 pools/d) despite the wide variance in plasma concentration. This suggests that differences in Lp(a) levels are caused by differences in synthesis rate. Indeed, the absolute synthetic rate of Lp(a) correlated directly with plasma Lp(a) concentration (P < 0.0001) in all subjects. The present results demonstrate that increased synthesis, rather than decreased catabolism, causes elevated plasma Lp(a) concentrations in the nephrotic syndrome.

scholarly journals Synthesis rate of plasma albumin is a good indicator of liver albumin synthesis in sepsis

2000 ◽  
Vol 279 (2) ◽  
pp. E244-E251 ◽  
Author(s):  
Benoît Ruot ◽  
Denis Breuillé ◽  
Fabienne Rambourdin ◽  
Gerard Bayle ◽  
Pierre Capitan ◽  
...  
Keyword(s):  
Synthesis Rate ◽  
Albumin Concentration ◽  
Liver Protein ◽  
Mrna Levels ◽  
Albumin Synthesis ◽  
Plasma Albumin ◽  
Period 2 ◽  
Fractional Synthesis ◽  
Plasma Albumin Concentration

Plasma albumin is well known to decrease in response to inflammation. The rate of albumin synthesis from both liver and plasma was measured in vivo by use of a large dose ofl-[2H3-14C]valine in rats injected intravenously with live Escherichia coli and in pair-fed control rats during the acute-phase period (2 days postinfection). The plasma albumin concentration was reduced by 50% in infected rats compared with pair-fed animals. Infection induced a fall in both liver albumin mRNA levels and albumin synthesis relative to total liver protein synthesis. However, absolute liver albumin synthesis rate (ASR) was not affected by infection. In plasma, albumin fractional synthesis rate was increased by 50% in infected animals compared with pair-fed animals. The albumin ASR estimated in the plasma was similar in the two groups. These results suggest that hypoalbuminemia is not due to reduced albumin synthesis during sepsis. Moreover, liver and plasma albumin ASR were similar. Therefore, albumin synthesis measured in the plasma is a good indicator of liver albumin synthesis.

scholarly journals Isolation of human skeletal muscle myosin heavy chain and actin for measurement of fractional synthesis rates

1998 ◽  
Vol 275 (6) ◽  
pp. E1092-E1099 ◽  
Author(s):  
D. L. Hasten ◽  
G. S. Morris ◽  
S. Ramanadham ◽  
K. E. Yarasheski
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Human Skeletal Muscle ◽  
Sodium Dodecyl ◽  
Synthesis Rate ◽  
Simple Method ◽  
Skeletal Muscle Myosin ◽  
Fractional Synthesis

Using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), we have developed a simple method to isolate myosin heavy chain (MHC) and actin from small (60–80 mg) human skeletal muscle samples for the determination of their fractional synthesis rates. The amounts of MHC and actin isolated are adequate for the quantification of [13C]leucine abundance by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Fractional synthesis rates of mixed muscle protein (MMP), MHC, and actin were determined in six healthy young subjects (27 ± 1 yr) after they received a 14-h intravenous infusion (prime = 7.58 μmol/kg body wt, constant infusion = 7.58 μmol ⋅ kg body wt−1 ⋅ h−1) of [1-13C]leucine. The fractional synthesis rates of MMP, MHC, and actin were found to be 0.0468 ± 0.0048, 0.0376 ± 0.0033, and 0.0754 ± 0.0078%/h, respectively. Overall, the synthesis rate of MHC was 20% lower ( P = 0.012), and the synthesis rate of actin was 61% higher ( P = 0.060, not significant) than the MMP synthesis rate. The isolation of these proteins for isotope abundance analysis by GC-C-IRMS provides important information about the synthesis rates of these specific contractile proteins, as opposed to the more general information provided by the determination of MMP synthesis rates.

scholarly journals ATP-dependent movement of myosin in vitro: characterization of a quantitative assay.

1984 ◽  
Vol 99 (5) ◽  
pp. 1867-1871 ◽  
Author(s):  
M P Sheetz ◽  
R Chasan ◽  
J A Spudich
Keyword(s):  
Skeletal Muscle ◽  
Actin Filaments ◽  
Quantitative Assay ◽  
Vitro Assay ◽  
Skeletal Muscle Myosin ◽  
In Vitro Characterization ◽  
Actin Cables ◽  
Muscle Myosin

Sheetz and Spudich (1983, Nature (Lond.), 303:31-35) showed that ATP-dependent movement of myosin along actin filaments can be measured in vitro using myosin-coated beads and oriented actin cables from Nitella. To establish this in vitro movement as a quantitative assay and to understand better the basis for the movement, we have defined the factors that affect the myosin-bead velocity. Beads coated with skeletal muscle myosin move at a rate of 2-6 micron/s, depending on the myosin preparation. This velocity is independent of myosin concentration on the bead surface for concentrations above a critical value (approximately 20 micrograms myosin/2.5 X 10(9) beads of 1 micron in diameter). Movement is optimal between pH 6.8 and 7.5, at KCl concentrations less than 70 mM, at ATP concentrations greater than 0.1 mM, and at Mg2+ concentrations between 2 and 6 mM. From the temperature dependence of bead velocity, we calculate activation energies of 90 kJ/mol below 22 degrees C and 40 kJ/mol above 22 degrees C. Different myosin species move at their own characteristic velocities, and these velocities are proportional to their actin-activated ATPase activities. Further, the velocities of beads coated with smooth or skeletal muscle myosin correlate well with the known in vivo rates of myosin movement along actin filaments in these muscles. This in vitro assay, therefore, provides a rapid, reproducible method for quantitating the ATP-dependent movement of myosin molecules on actin.

scholarly journals Assembly of smooth muscle myosin into side-polar filaments.

1977 ◽  
Vol 75 (3) ◽  
pp. 990-996 ◽  
Author(s):  
R Craig ◽  
J Megerman
Keyword(s):  
Smooth Muscle ◽  
Opposite Polarity ◽  
Skeletal Muscle Myosin ◽  
Myosin Filaments ◽  
Skeletal Myosin ◽  
Cross Bridges ◽  
Bipolar Filament ◽  
Muscle Myosin

The in vitro assembly of myosin purified from calf aorta muscle has been studied by electron microscopy. Two types of filament are formed: short bipolar filament similar to those formed from skeletal muscle myosin, and longer "side-polar" filaments having cross bridges with a single polarity along the entire length of one side and the opposite polarity along the other side. Unlike the case with skeletal myosin filaments, antiparallel interactions between myosin molecules occur along the whole length of side-polar filaments. The side-polar structure may be related to the in vivo form of myosin in vertebrate smooth muscle.

scholarly journals Tendon collagen synthesis at rest and after exercise in women

2007 ◽  
Vol 102 (2) ◽  
pp. 541-546 ◽  
Author(s):  
Benjamin F. Miller ◽  
Mette Hansen ◽  
Jens L. Olesen ◽  
Peter Schwarz ◽  
John A. Babraj ◽  
...  
Keyword(s):  
Luteal Phase ◽  
Collagen Synthesis ◽  
Synthesis Rate ◽  
Menstrual Phase ◽  
Late Luteal Phase ◽  
Significant Difference ◽  
Healthy Female ◽  
Early Follicular Phase ◽  
Fractional Synthesis ◽  
Tendon Collagen

In general, there is a higher incidence of musculoskeletal injuries during physical activity in women than in men. We hypothesized that in women rates of tendon collagen synthesis would be lower than in men at rest and after exercise, especially in the later luteal phase when estrogen and progesterone concentrations are higher than the early follicular phase. We studied tendon collagen fractional synthesis rate (FSR) in 15 young, healthy female subjects in either the early follicular ( n = 8) or the late luteal phase ( n = 7) 72 h after an acute bout of one-legged exercise (60 min kicking at 67% workload maximum) (72 h) and compared the results with those previously obtained for men. Samples were taken from the patellar tendon in both the exercised and rested legs to determine collagen FSR by the incorporation of [15N]proline into tendon collagen hydroxyproline. There was no effect of menstrual phase on tendon collagen synthesis either at rest or after exercise. However, there was a significant difference between women and men at rest (women = 0.025 ± 0.002%/h, men = 0.045 ± 0.008%/h; P < 0.05) and 72 h after exercise (women = 0.027 ± 0.005%/h; men = 0.058 ± 0.008%/h). Furthermore, rest and 72-h tendon collagen synthesis were not different in women, whereas in men tendon collagen synthesis remained significantly elevated 72 h after exercise. It is concluded that both in the resting state and after exercise, tendon collagen FSR is lower in women than in men, which may contribute to a lower rate of tissue repair after exercise.

scholarly journals Protein synthesis in rat lung. Measurements in vivo based on leucyl-tRNA and rapidly turning-over procollagen I

1984 ◽  
Vol 222 (1) ◽  
pp. 77-83 ◽  
Author(s):  
J Kelley ◽  
W S Stirewalt ◽  
L Chrin
Keyword(s):  
Plasma Proteins ◽  
Specific Radioactivity ◽  
Young Male ◽  
Male Rats ◽  
Synthesis Rate ◽  
Vascular Perfusion ◽  
Fractional Synthesis ◽  
Free Serum ◽  
Procollagen Iii

The relationships of the specific radioactivities of leucine in serum, leucine acylated to tRNA and leucine in procollagen I, procollagen III and total protein in lungs of unanaesthetized young male rats in vivo were assessed as a function of time during constant intravenous infusion of radiolabelled leucine. The specific radioactivity of free leucine in plasma reached a steady-state plateau value within 30 min of initiation of [3H]leucine infusion. Leucine acylated to tRNA isolated from lungs had the same specific radioactivity as free serum leucine. Leucine in procollagen I rapidly achieved a specific radioactivity equal to that of serum leucine and leucyl-tRNA, indicating that serum leucine and leucyl-tRNA isolated from total lung were in rapid equilibrium with the precursor leucine pool for procollagen I synthesis. On the basis of leucyl-tRNA or free serum leucine as the precursor, half-times of fractional conversion of procollagen I and III were calculated as 9 and 38 min respectively. The incorporation of leucine into mixed lung proteins calculated from the tracer studies was 6.8 mumol/day for the first 30 min of the infusion, after which the calculated rate increased to 15.0 mumol/day. This apparent increase correlated with the appearance of rapidly labelled plasma proteins trapped in the lungs. On the basis of short infusions lasting 30 min or less, followed by vascular perfusion of the lung, the average fractional synthesis rate of mixed pulmonary proteins in young male rats was 20%/day.

Mixed muscle protein synthesis and breakdown after resistance exercise in humans

1997 ◽  
Vol 273 (1) ◽  
pp. E99-E107 ◽  
Author(s):  
S. M. Phillips ◽  
K. D. Tipton ◽  
A. Aarsland ◽  
S. E. Wolf ◽  
R. R. Wolfe
Keyword(s):  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Exercise Bout ◽  
Synthesis Rate ◽  
Breakdown Rate ◽  
Time Points ◽  
Significant Difference ◽  
Fractional Synthesis ◽  
Exercise In Humans

Mixed muscle protein fractional synthesis rate (FSR) and fractional breakdown rate (FBR) were examined after an isolated bout of either concentric or eccentric resistance exercise. Subjects were eight untrained volunteers (4 males, 4 females). Mixed muscle protein FSR and FBR were determined using primed constant infusions of [2H5]phenylalanine and 15N-phenylalanine, respectively. Subjects were studied in the fasted state on four occasions: at rest and 3, 24, and 48 h after a resistance exercise bout. Exercise was eight sets of eight concentric or eccentric repetitions at 80% of each subject's concentric 1 repetition maximum. There was no significant difference between contraction types for either FSR, FBR, or net balance (FSR minus FBR). Exercise resulted in significant increases above rest in muscle FSR at all times: 3 h = 112%, 24 h = 65%, 48 h = 34% (P < 0.01). Muscle FBR was also increased by exercise at 3 h (31%; P < 0.05) and 24 h (18%; P < 0.05) postexercise but returned to resting levels by 48 h. Muscle net balance was significantly increased after exercise at all time points [(in %/h) rest = -0.0573 +/- 0.003 (SE), 3 h = -0.0298 +/- 0.003, 24 h = -0.0413 +/- 0.004, and 48 h = -0.0440 +/- 0.005], and was significantly different from zero at all time points (P < 0.05). There was also a significant correlation between FSR and FBR (r = 0.88, P < 0.001). We conclude that exercise resulted in an increase in muscle net protein balance that persisted for up to 48 h after the exercise bout and was unrelated to the type of muscle contraction performed.

scholarly journals Measurement of dermal collagen synthesis rate in vivo in humans

1998 ◽  
Vol 274 (4) ◽  
pp. E586-E591 ◽  
Author(s):  
Wassim A. El-Harake ◽  
Mikhail A. Furman ◽  
Brian Cook ◽  
K. Sreekumaran Nair ◽  
Jayme Kukowski ◽  
...  
Keyword(s):  
Collagen Synthesis ◽  
Current Method ◽  
Synthesis Rate ◽  
Tissue Fluid ◽  
Disease States ◽  
Human Volunteers ◽  
Human Proteins ◽  
Dermal Collagen ◽  
Fractional Synthesis

Accumulation of collagen produces organ dysfunction in many pathological conditions. We measured the fractional synthesis rate (FSR) of dermal collagen in five human volunteers from the increment of [13C]proline in detergent-soluble dermal collagen hydroxylated to hydroxyproline during a continuous infusion ofl-[1-13C]proline. In these and eight other volunteers, we measured [13C]proline enrichment in skin aminoacyl-tRNA, skin tissue fluid amino acid, and plasma. The prolyl-[13C]tRNA enrichment was one-half that in tissue fluid proline and more than threefold less than in plasma. The FSR of dermal collagen was 0.076 ± 0.063%/h (mean ± SD), similar to previously reported rates for skeletal muscle contractile proteins and substantially slower than hepatically derived circulating proteins such as albumin or fibrinogen. We conclude that the FSR of human dermal collagen resembles that of other human proteins considered to display slow turnover. The current method for its measurement may be used to determine the regulation of collagen synthesis in other organs and disease states.

scholarly journals Highly selective inhibition of myosin motors provides the basis of potential therapeutic application

2016 ◽  
Vol 113 (47) ◽  
pp. E7448-E7455 ◽  
Author(s):  
Serena Sirigu ◽  
James J. Hartman ◽  
Vicente José Planelles-Herrero ◽  
Virginie Ropars ◽  
Sheila Clancy ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Muscle Relaxation ◽  
Selective Inhibition ◽  
Pharmacological Agents ◽  
Skeletal Muscle Myosin ◽  
Starting Point ◽  
Myosin Motors ◽  
Muscle Myosin

Direct inhibition of smooth muscle myosin (SMM) is a potential means to treat hypercontractile smooth muscle diseases. The selective inhibitor CK-2018571 prevents strong binding to actin and promotes muscle relaxation in vitro and in vivo. The crystal structure of the SMM/drug complex reveals that CK-2018571 binds to a novel allosteric pocket that opens up during the “recovery stroke” transition necessary to reprime the motor. Trapped in an intermediate of this fast transition, SMM is inhibited with high selectivity compared with skeletal muscle myosin (IC50 = 9 nM and 11,300 nM, respectively), although all of the binding site residues are identical in these motors. This structure provides a starting point from which to design highly specific myosin modulators to treat several human diseases. It further illustrates the potential of targeting transition intermediates of molecular machines to develop exquisitely selective pharmacological agents.

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