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:3.6.4.1 (myosin ATPase)
1,140 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

F-actin monomer (F-monomer) is formed upon the addition of neutral salt to G-actin. Since F-monomer has a digestibility similar to that of F-actin and much lower than that of G-actin, it has been proposed that F-monomer has a conformation different from that of G-actin and similar to the conformation of the subunits in F-actin. To examine whether F-monomer will enhance the magnesium-activated myosin adenosine triphosphatase (Mg2+-ATPase) as much as F-actin, the ability of partially polymerized actin populations at equilibrium to activate the Mg2+-ATPase of heavy meromyosin was investigated. Correlations were made between ATPase activities and the polymerization state of actin as determined by measurements of viscosity and digestibility. No significant activation of the heavy meromyosin ATPase was observed under conditions where G-actin or mixtures of G-actin and F-monomer were present. As polymer formation occurred at higher actin concentrations, or with increased KCl concentrations, substantial activation characteristic of F-actin was observed. The data suggest that F-monomer may undergo a further conformational change as it forms nuclei or joins onto polymers. Alternatively, the site of actin which activates the myosin ATPase may involve the crevice between two adjacent actin subunits.
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PMID:Activation of heavy meromyosin adenosine triphosphatase by various states of actin. 15 Feb 86

Myosin has been purified from the principal pancreatic islet of catfish, hog salivary gland, and hog pituitary. Use of the protease inhibitor Trasylol (FBA Pharmaceuticals, New York) was essential in the isolation of pituitary myosin. Secretory tissue myosins were very similar to smooth muscle myosin, having a heavy chain of 200,000 daltons and light chains of 14,000 and 19,000 daltons. Salivary gland myosin cross-reacted with antibodies directed toward both smooth muscle myosin and fibroblast myosin, but not with antiskeletal muscel myosin serum. The specific myosin ATPase activity measured in 0.6 M KCl was present. Tissues associated with secretion of hormone granules contained substantial amounts of this ATPase, rat pancreatic islets having 4.5 times that of rat liver. Activation of low ionic strength myosin ATPase by actin could not be demonstrated despite adequate binding of the myosin to muscle actin and elution by MgATP. The myosins were located primarily in the cytoplasm as determined by cell fractionation and were quite soluble in buffers of low ionic strength.
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PMID:Myosins of secretory tissues. 15 Apr 27

Pre and perinatal malnutrition of rats was effected by means of limiting the mothers' food intake by 50% during pregnancy and lactation. Male offspring were sacrificed at 36 weeks of age and the anterior tibialis (ANTIB) and soleus (SOL) muscles were prepared for histochemical demonstration of Type I, IIA and IIB muslce fibre types using myosin ATPase and succinic dehydrogenase activity. Muscle weights and mean muscle fibre area determinations showed greater decreases in ANTIB than SOL, SOL muscle fibre areas being relatively unaffected by the undernutrition regimen. The proportions present of the muscle fibre types differed in ANTIB and to a small extent on SOL. In the former muscle, some decreases in area in certain of the fibres were associated with increases in the percentages present, showing a tendency to maintain the physiological cross-sectional area of the muscle.
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PMID:Effects of pre and perinatal malnutrition on muscle fibres from fast and slow rat muscles. 15 Jun 34

Myosin was purified from the flight muscles of a flying (pigeon) and a nonflying (fowl) bird. Ki (ADP) of myosin ATPase of pigeon is higher, but the Km (ATP) is lower than that of fowl. The specific activity (mumole of Pi liberated/min/mg protein) is higher for the fowl. A0.5 (CaCl2) of myosin of both pigeon and fowl is similar. However, the two proteins differ in their interactions with ADP, ATP and p-chloromercuribenzoate. The two proteins have the same tyrosine, tryptophan and sulfhydryl contents. The electrophoretic patterns of the two myosins on SDS-polyacrylamide gels are different. These studies show significant molecular differences in the myosin derived from the flight muscles of a flying (pigeon) and a nonflying (fowl) bird.
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PMID:Comparative studies on myosin ATPase of a flying and nonflying bird. 15 58

Changes in cardiac metabolism in myocardial failure and after alcohol ingestion are discussed. The main effect of alcohol ingestion is loss of cardiac contractility. Since heart muscle does not contain alcohol dehydrogenase, its toxicity is probably the result of a direct toxic effect of ethanol and acetaldehyde on the myocardial cell, possibly involving various membrane systems. Alcohol inhibits mitochondrial respiration and the activity of enzymes in the tricarboxylic acid cycle, and its interferes with both mitochondrial calcium uptake and binding. Ethanol profoundly affects myocardial lipid metabolism. Acetaldehyde diminishes myocardial protein synthesis and inhibits Ca++-activated myofibrillar ATPase. In myocardial failure, a series of possibilities may be responsible for the loss of contractility. Excitation-contraction coupling could be disturbed at the level of the sarcolemma, at the sarcoplasmic reticulum, at the mitochondria, and between calcium and the regulatory proteins. Deficiencies in Ca++ delivery systems of excitation-contraction coupling on the myosin ATPase activity could be responsible for the dimunition in cardiac contractility. Mitochondrial function may also be involved, since mitochondria from failing human hearts are defective with respect to respiratory control and calcium accumulation. Under certain conditions, the relationship of mitochondria to calcium sequestration is very important in influencing contractility. The involvement of contractile and regulatory proteins in myocardial failure cannot be excluded.
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PMID:Cardiac metabolsim: its contributions to alcoholic heart disease and myocardial failure. 15 68

Myosin light chain kinases have been isolated from rat thigh and rabbit skeletal muscle and cultured rat myoblasts. From these preparations, two types of kinases can be distinguished: calcium-dependent and calcium-independent. Both types of kinases can phosphorylate isolated P-light chains of myosin from several sources (skeletal muscle, cardiac muscle, and platelet). Data are shown which support the phosphorylation of the same site on the non-muscle P-light chains by both types of kinases. The rates of these reactins are, however, different for the two types of kinases. Kinetic analysis of the myoblast kinase shows differing affinities for various P-light chains (non-muscle greater than cardiac greater than skeletal). In the proliferative rat myoblast, phosphorylation of myosin is a prerequisite for actin activation of the myosin ATPase activity.
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PMID:A comparative study of the myosin light chain kinases from myoblast and muscle sources. Studies on the kinases from proliferative rat myoblasts in culture, rat thigh muscle, and rabbit skeletal muscle. 15 62

Mitotic PtK1 cells, lysed at anaphase into a carbowax 20 M Brij 58 solution, continue to move chromosomes toward the spindle poles and to move the spindle poles apart at 50% in vivo rates for 10 min. Chromosome movements can be blocked by adding metabolic inhibitors to the lysis medium and inhibition of movement can be reversed by adding ATP to the medium. Vanadate at micromolar levels reversibly inhibits dynein ATPase activity and movement of demembranated flagella and cilia. It does not affect glycerinated myofibril contraction or myosin ATPase activty at less than millimolar concentrations. Vanadate at 10--100 micron reversibly inhibits anaphase movement of chromosomes and spindle elongation. After lysis in vanadate, spindles lose their fusiform appearance and become more barrel shaped. In vitro microtubule polymerization is insensitive to vanadate.
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PMID:Chromosome movement in lysed mitotic cells is inhibited by vanadate. 15 67

Papillary muscle mechanics and ventricular myosin calcium-activated ATPase activity were measured in the same heart as a function of temperature (8--28 degrees) in rabbits and marmots, in order to examine further the hypothesis that the velocity of cardiac muscle shortening at zero load (Vmax) is correlated with myosin ATPase activity. There was a similar Q10 for Vmax in each muscle type, as measured with isotonic afterloaded quick-releases at 30--33% time-to-peak tension; the calcium activated ATPase of myosin in the two muscle types also was similar. The least squares linear regression of rabbit Vmax on calcium-activated myosin ATPase activity was the same as in the marmot, so all the data were pooled to yield a linear regression (Y = 0.47 +/- 3.82X) with a high correlation between the two variables [r = 0.95, P less than 0.01 (ANOV)]. Furthermore, the correlation proved to be predictive of cardiac Vmax and myosin ATPase activity levels in other experiments where these two measurements decreased below normal as a result of hypertrophic growth. Consequently, the quantitative relationship between Vmax and myosin ATPase defined here may prove to be predictive of the ability of cardiac muscle to release bond energy.
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PMID:The relationship of mechanical Vmax to myosin ATPase activity in rabbit and marmot ventricular muscle. 15 23

Changes in some values of protein metabolism in the heart muscle (the activity of myosin ATPase, leucilaminopeptidase, glutamate dehydrogenase, as well as the content of SH-groups, urea, RNA and DNA) were studied by histochemical methods in the parts of the myocardium remote from the zone of the ligated coronary artery. Disorders in the metabolism of nucleic acids were found to consist in nuclear polymorphism and in the development of regressive changes in some nuclei down to necrobiosis as well as in a decrease of the RNA content within the first 12 hours after ligation of the coronary artery. Subsequently, the amount of RNA increased. An increase in the amount of SH-groups, in the activity of leucilaminopeptidase and a decrease in the amount of glutamate dehydrogenase, formation of crystals of xanthhydrolurea as well as in increase in the activity of myosin ATP-ase early in the experiment attest to the occurrence of heterogeneous disorders of protein metabolism in parts of the myocardium beyond the infarction zone.
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PMID:[Histochemical data on changes of various indicators of protein metabolism in the myocardium beyond the infarct zone]. 15 40

In our previous study (Onishi, H., Susuki, H., Nakamura, k., and Watanabe, S. J. Biochem. 83, 835-847, 1978), we found it to be characteristic of chicken gizzard myosin that thick filaments of gizzard myosin are readily disassembled by a stoichiometric amount of ATP (3 mol of ATP per mol of myosin), and that the ATPase activity of gizzard myosin in the ATP-disassembled state is much lower than that of gizzard myosin disassembled by a high concentration of KCl. We now report the following findings: (1) Thick filaments of (unphosphorylated) gizzard myosin can be in a bipolar structure or in a non-polar structure, depending on the method of preparing the thick filaments. (2) Thick filaments of (unphosphorylated) gizzard myosin in either the bioplar or the non-polar structure are readily disassembled by ATP. (3) Addition of rabbit skeletal C-protein does not confer ATP resistance on thick filaments of (unphosphorylated) gizzard myosin. (4) Unphosphorylated) gizzard myosin in the ATP-disassembled state is in a dimeric form as determined by ultracentrifugation. Moreover, 0.2 M KCl-dissociated gizzard myosin in monomeric form is converted to a dimeric form by ATP. (5) The Mg-ATPase activity of (unphosphorylated) gizzard myosin is much lower in its dimeric form (less than one-tenth) than in its monomeric form. The activity depression observed around 0.15 M KCl is therefore due to the formation of myosin dimers. (6) Skeletal L-meromyosin can increase the very low activity of (unphosphorylated) gizzard myosin ATPase at low ionic strength (0.13 M KCl) by forming ATP-resistant hybrid filaments with (unphosphorylated) gizzard myosin, preventing the formation of myosin dimers. (7) Gizzard myosin in which one of the light-chain components is phosphorylated by myosin light-chain kinase can form thick filaments which are resistant to the disassembling action of ATP. (8) Even in the presence of ATP, thick filaments of phosphorylated gizzard myosin do not disassembled into myosin dimers. Accordingly, the ATPase activity of phosphorylated gizzard myosin does not show activity depression at low ionic strength.
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PMID:Structure and function of chicken gizzard myosin. 15 5


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