Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Corticosteroid myopathy was studied in young, mature New Zealand white rabbits given daily injections of betamethasone (0.3 mg/kg body weight/day) for two weeks. Control rabbits were pair-fed and received saline injections. Bethamethasone treatment caused significant wasting of type 2 gluteus medius and psoas muscles but did not cause any atrophy of type 1 soleus and gluteus minimus muscles. The Mg2+- and Ca2+-activated myofibrillar ATPase activities of the corticosteroid-treated rabbits did not differ from controls despite a 30% reduction in muscle wet weight and pronounced reduction in cross-sectional area of fibers. SDS-polyacrylamide gel electrophoresis profiles of myofibrillar proteins did not differ quantitatively or qualitatively between experimental and control rabbits. Studies of net muscle protein degradation (using 3H-leucine) in betamethasone-treated and control rabbits indicate that both type 1 and type 2 muscle fiber proteins are degraded several times faster in the corticosteroid-treated group. This suggests that a compensatory mechanism exists for those type 1 and mixed fiber type muscles which have increased degradation but do not undergo wasting.
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PMID:Experimental corticosteroid myopathy: effect on myofibrillar ATPase activity and protein degradation. 15 6

The effect of medium Ca2+ concentration upon the concentration and the rate of synthesis of muscle proteins was investigated in chicken pectoralis muscle cultures. There is an easily identifiable class of muscle protein which includes the Ca2+-ATPase of sarcoplasmic reticulum, myosin, troponin C, ATP : creatine phosphotransferase, muscle specific actin, tropomysin 1 and 2, and muscle hemagglutinin, which show a large increase in concentration during normal development. The increased synthesis of these proteins was inhibited, without inhibition of cell proliferation, in culture media of relatively low Ca2+ concentration, 0.05--0.3 mM, where fusion was prevented. Similar medium Ca2+ concentration was required for the expression of all these proteins, suggesting their coordinate regulation. The proteins are denoted as 'calcium-modulated proteins'. The increased Ca2+ transport activity of sarcoplasmic reticulum in cultured chicken pectoralis muscle cells during development at 1.8 mM medium calcium concentration represents de novo synthesis of the Ca2+ transport ATPase, as shown by immunoprecipitation, active site labeling and direct identification of the Ca2+ transport ATPase on two-dimensional gel electropherograms of whole muscle homogenates. The concentration and the turnover rate of the majority of the muscle proteins is not affected significantly by medium Ca2+ concentration between 0.06 and 1.8 mM. It is proposed that increase in cytoplasmic free Ca2+ concentration during fusion plays a central role in the regulation of the synthesis of calcium-modulated proteins.
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PMID:Synthesis of the calcium transport ATPase of sarcoplasmic reticulum and other muscle proteins during development of muscles cells in vivo and in vitro. 22 45

The action on muscle proteins of microbial transglutaminase (MTGase), which catalyzes the formation of a "zero-length" covalent cross-link between glutamine and lysine residues in peptides, was studied in order to define a basis for future application of MTGase cross-linking to the study of muscle protein interaction. We examined the cross-linking of skeletal muscle myosin, myosin subfragments, actin, and myofibrils by treatment with MTGase and the possible side-effects of the cross-linking on the enzymic activity of myosin, and found that the rod portions of myosin in myosin filaments were quickly cross-linked to each other by the action of MTGase, but myosin subfragment 1 was not cross-linked to actin. The MgATPase activities at 0.5 M KCl of myosin, heavy meromyosin, subfragment 1, and subfragment 1-actin were not significantly affected by the MTGase reaction. A very small fraction of the head portion of heavy meromyosin was cross-linked to actin in their rigor complexes by MTGase, and the ATPase activity at 0.5 M KCl of the cross-linked heavy meromyosin-actin complexes was slightly enhanced.
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PMID:Cross-linking of contractile proteins from skeletal muscle by treatment with microbial transglutaminase. 135 72

mAbs specific for protein components of the surface membrane of rabbit skeletal muscle have been used as markers in the isolation and characterization of skeletal muscle sarcolemma membranes. Highly purified sarcolemma membranes from rabbit skeletal muscle were isolated from a crude surface membrane preparation by wheat germ agglutination. Immunoblot analysis of subcellular fractions from skeletal muscle revealed that dystrophin and its associated glycoproteins of 156 and 50 kD are greatly enriched in purified sarcolemma vesicles. The purified sarcolemma was also enriched in novel sarcolemma markers (SL45, SL/TS230) and Na+/K(+)-ATPase, whereas t-tubule markers (alpha 1 and alpha 2 subunits of dihydropyridine receptor, TS28) and sarcoplasmic reticulum markers (Ca2(+)-ATPase, ryanodine receptor) were greatly diminished in this preparation. Analysis of isolated sarcolemma by SDS-PAGE and densitometric scanning demonstrated that dystrophin made up 2% of the total protein in the rabbit sarcolemma preparation. Therefore, our results demonstrate that although dystrophin is a minor muscle protein it is a major constituent of the sarcolemma membrane in skeletal muscle. Thus the absence of dystrophin in Duchenne muscular dystrophy may result in a major disruption of the cytoskeletal network underlying the sarcolemma in dystrophic muscle.
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PMID:Dystrophin-glycoprotein complex is highly enriched in isolated skeletal muscle sarcolemma. 198 2

We previously showed that radioactive N-ethylmaleimide injected intramuscularly reacts with actomyosin and other muscle proteins and that a transfer of these modified proteins to lysosome-rich large granules was associated with their degradation (Gerard, K. W., and Schneider, D. L., (1979) J. Biol. Chem. 254, 11798-11805). We now show that muscle cells, when challenged by an increase in proteins modified with N-ethylmaleimide, can increase degradation by increasing the activities of enzymes involved in protein turnover. Cathepsin B activity increased 2-fold 36 h after injection of N-ethylmaleimide. In contrast, non-lysosomal proteolytic enzymes, calcium-dependent protease, and leucine aminopeptidase, did not significantly increase. Lysosomes are also involved in the degradation of normal muscle proteins labeled with [3H]leucine. Treatment with chloroquine, a known inhibitor of lysosome function, resulted in an inhibition of protein degradation, in an increase of the muscle protein content, and in the accumulation of radioactive proteins in lysosomal fractions. Chloroquine treatment for 2 days led to a 270% increase in cathepsin B and a 160% increase in lysosomal ATPase activities, but only a 30% increase in neutral proteinase activities. These results indicate a role for lysosomes in regulation of protein turnover in muscle.
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PMID:Degradation of intracellular protein in muscle. Lysosomal response to modified proteins and chloroquine. 319 4

Clofibrate, a hypolipidemic agent, has been shown to increase muscle protein degradation. The possible role of thyroid hormones in this phenomena was examined. Clofibrate treatment of rats for 2 weeks resulted in a significant decrease in total thyroxine and triiodothyronine levels in serum. Reverse T3 and resin uptake values remained unchanged. When exogenous thyroxine was co-administered with clofibrate, serum TSH levels were suppressed, but the increased muscle protein degradation was not reversed. Equilibrium dialysis and Scatchard analysis of the binding of 125I-thyroxine to serum proteins indicated that clofibrate competitively inhibits the binding of thyroid hormone to serum proteins by decreasing its apparent binding affinity. In the presence of lower total thyroid hormone concentrations and an elevated free thyroxine fraction, the total free hormone levels are estimated to be in the normal range in the serum of clofibrate treated rats. Clofibrate seems to act like thyroid hormone since it binds to and displaces T4 from plasma proteins. Because free thyroid hormone levels are in the normal range, the thyroid hormone-like effects of clofibrate on the cell may be additive to the T4 effects, and are probably responsible for the hypermetabolic state seen in the muscle of clofibrate-treated animals. Our data suggest that the effects of clofibrate in muscle are complex. In addition to competitively altering the binding of thyroxine to serum proteins, this substance may also exert a hitherto unrecognized thyroid-hormone-like subcellular effect resulting in increased muscle protein degradation, and in augmented ouabain-sensitive ATPase activities.
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PMID:Influence of clofibrate on thyroid hormone and muscle protein turnover. 643 38

A study was undertaken to determine if sustained administration of isoproterenol (ISO) alters biochemical and functional properties of hearts and the submaximal and maximal exercise capacity of rodents. Compared with sham-treated controls of the same age, sex, and body weight, 4 wk of ISO (0.2--0.4 mg/kg sc) produced an approximate 30% increase in combined ventricle wet weight (P less than 0.001). Respiratory capacity of homogenates, total muscle protein concentration, and actomyosin and myofibril ATPase of heart muscle of the ISO-treated group were the same as in the control group. Various cardiac function parameters in situ, obtained under control conditions and in response to tyramine-induced norepinephrine release, were similar for the two groups. ISO-treated rats had slightly greater endurance for running submaximally on a treadmill than the control rats (P less than 0.10), but their maximal capacity to utilize oxygen (VO2max) was not different from controls. These findings suggest that rodent hearts moderately enlarged by relatively low doses of isoproterenol possess normal metabolic and functional capacity. However, this cardiac enlargement had no apparent effect on maximal exercise performance of the whole animal.
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PMID:Exercise capacity and cardiac function of rats with drug-induced cardiac enlargement. 646 21

A simple, improved procedure for the isolation of the phosphotyrosyl phosphatase activator (PTPA) from rabbit skeletal muscle has been developed. The majority of the protein phosphatase 2A (PP2A) was separated from PTPA at an early stage in the procedure. The procedure yields approximately 1 mg essentially pure PTPA/kg rabbit skeletal muscle; it was also applied to porcine brain and the yeast Saccharomyces cerevisiae. The physico-chemical properties of PTPA obtained from all sources are very similar. The pure rabbit skeletal muscle protein was used to raise polyclonal goat antibodies and to affinity purify these antibodies. Immunological studies revealed the presence of PTPA in all mammalian tissues and cell lines examined with differences in tissue distribution, brain showing the highest concentration. PTPA could only be detected in cytosolic fractions. Using a semi-quantitative immunological assay (Western blot), the in vivo concentration could be estimated to be micromolar, which is in the same range as the PP2A target. The purified Xenopus oocyte PTPA showed only a weak cross reactivity, whereas yeast PTPA was not recognised by the antibody indicating some evolutionary diversity of the protein. In a PTPA-affinity column chromatography, the weak interaction with PP2A was independent of the presence of ATP.Mg, a necessary cofactor in the activation process. Interaction of PTPA with PP2A in a 1:1 ratio induces a low (kcat = 3 min-1) ATPase activity that is inhibited by okadaic acid, ADP and non-hydrolysable ATP analogues.
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PMID:The phosphotyrosyl phosphatase activator of protein phosphatase 2A. A novel purification method, immunological and enzymic characterization. 781 81

In anesthetized rats, injection of the beta 2-adrenoceptor (beta 2-AR) agonist clenbuterol (0.45 mumol/kg) caused a marked stimulation of 86RbCl (Rb) uptake by skeletal muscle, but had no effect on other tissues; soleus muscle showed the largest (144% increase) response. Injection of another beta 2-AR agonist (salbutamol 0.45 mumol/kg) had no effect on Rb uptake by any tissue except soleus muscle (83%). Both agonists increased body (colonic) temperature to the same extent. A 3-day treatment with salbutamol as a dietary admixture had no effect on body weight, muscle mass, or tissue Rb uptake, whereas the same treatment using clenbuterol produced significant increases in body weight and muscle mass and significant decreases in Rb uptake in three of the four muscle groups studied; Rb uptake in soleus was not affected. In another experiment, the short-term effect of clenbuterol injection on muscle Rb uptake was found to be resistant to a high dose (20 mg/kg) of the selective beta 2-AR antagonist ICI 118551. It was concluded that the selective effects of short-term administration of clenbuterol on muscle Rb uptake, coupled with its effects over 3 days on Rb uptake and muscle hypertrophy, implicate beta-AR modulation of cation transport (possibly via Na,K-adenosine triphosphatase [ATPase] activity) in the anabolic effects of clenbuterol on muscle protein deposition. Since the stimulation of Rb uptake by clenbuterol was resistant to high doses of a selective beta 2-AR antagonist and since salbutamol had little or no effect on muscle hypertrophy or Rb uptake, it is suggested that clenbuterol may exert its effects via an atypical beta-AR.
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PMID:Effects of clenbuterol and salbutamol on tissue rubidium uptake in vivo. 785 56

A sensitive enzyme-linked immunoadsorbant assay was developed to quantify Ca(2+)-ATPase and calsequestrin from sarcoplasmic reticulum in human muscle biopsies. Tissue levels of Ca(2+)-ATPase and calsequestrin averaged 51.5 +/- 28.1 and 6.4 +/- 1.8 mg/g muscle protein, respectively, in control muscles (means +/- SD, n = 12). The high sensitivity and specificity of the antibodies make the assay a useful tool in the diagnosis of human neuromuscular disorders where defects in sarcoplasmic reticulum function may be expected. The assay was applied to muscle biopsies from patients with myotonia congenita and paramyotonia congenita Eulenburg. The calsequestrin concentration was normal in all patient muscles. The Ca(2+)-ATPase content was also within the normal range but varied considerably with the percentage distribution of slow-twitch fibres. This indicates that the prolonged relaxation observed in the muscles of patients with these disorders is not caused by faulty expression of Ca(2+)-ATPase and calsequestrin.
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PMID:Immunochemical quantification of sarcoplasmic reticulum Ca(2+)-ATPase and calsequestrin in muscle biopsies from patients with myotonia congenita and paramyotonia congenita Eulenburg. 785 84


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