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)

Solution of thrombosthenin, the contractile protein complex isolated from pig platelets, have been studied by analytical ultracentrifugation and zone sedimentation in sucrose density gradients. Freshly prepared thrombosthenin in 0.6 M KCl shows a prominent peak in the ultracentrifuge with S degrees 20w about 5.5 and higher molecular weight aggregates (greater than 100S) sedimenting quickly to the bottom of the cell. Short term storage of high ionic strength solutions of thrombosthenin induces actomyosin-like gel formation and these gels dissociate with ATP and Mg2+ ions into two components of S degrees 20w 8.0 and S degrees 20w50. The supernatant, after actomyosin gel removal, contains only the S degrees 20w5.5 protein. From results of Ca2+ ATPase activity measurements and SDS polyacrylamide gel electrophoretic mobilities of dissociated thrombosthenin separated into fractions in sucrose density gradients, it is concluded that the S degrees20w5.5 protein species is the myosin-like protein of thrombosthenin. The S degrees 20w8.0 protein is not fibrinogen but also has myosin-like properties and is believed to be myosin dimer. Species of higher S values seen in the presence of ATP and Mg2+ in the analytical ultracentrifuge and located in the higher density zones of the sucrose gradients all gave in SDS polyacrylamide gel electrophoresis a single band of molecular weight 46-47,000 daltons. These subunit proteins appear to be derived from a range of polymeric variants of the F-actin-like protein of the contractile complex. All these higher density F-actin-like proteins readily form superprecipitates and display syneresis when combined with rabbit skeletal muscle myosin or platelet myosin. They are also all capable of conferring upon these two myosins a Mg2+ activated ATPase activity. It is suggested that in thrombosthenin solutions a myosin monomer-dimer equilibrium state exists which can be directionally influenced by a number of factors. The coexistence in the solution of F-actin and Mg2+ ATP, for example, increases the propensity of the myosin-like protein to form the higher molecular weight aggregate. Such aggregation may be the initiating mechanism for the intracellular organization of the thick filaments of the actomyosin complex, preparatory to a contractile event.
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PMID:Platelet contractile proteins: separation and characterization of the actin and myosin-like components. 12 96

A myosin-like protein was identified in isolated rabbit liver cells. It was extracted with high-ionic-strength buffer containing ATP, and purified by gel filtration in the presence of iodide. The myosin polypeptide was indistinguishable in size from the heavy chain of muscle myosin as determined by electrophoresis on polyacrylamide gels and gel filtration in the presence of sodium dodecyl sulfate. The hepatic myosin had an amino acid composition similar to that of muscle myosin, but lacked 3-methylhistidine. The Mg2+ -ATPase of the myosin was not activated by muscle actin. At low ionic strength, in the presence of Mg2+, the protein aggregated to form bipolar filaments 0.3 mum in length. A protein which resembled muscle actin in size and amino acid composition was extracted along with the myosin. Based on scans of stained sodium dodecyl sulfate polyacrylamide gels, the myosin content was estimated as 0.3% to 0.4% of the cell protein. The actin-like component was present in approximately ten-fold excess by weight. This ratio suggests that the organization and function of myosin in the hepatocyte is very different from that in the muscle cell.
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PMID:The identification of myosin in rabbit hepatocytes. 13 48

The plain synaptic vesicle and the ocated vesicle fractions were isolated from rat brains, and the ATPase [EC 3.6.1.3] activities were characterized in terms of ionic effects, drug effects, and protein components. Coated vesicle fraction contained three times as much actomysin-like proteins as plain vesicle fraction, although both fractions had an identical ratio of actin-like protein to myosin-like protein. The ATPases of these two fractions were activated by both Mg2+ and Ca2+, and, in the presence of either of the cations, were inhibited by KCl. Reserpine activated plain vesicle ATPase only in the presence of Cl-. Colchicine and vinblastine inhibited coated vesicle ATPase only. The results are consistent with the view that actomyosin-like proteins are involved in the synaptic retrieval process.
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PMID:Characterization of ATPases of plain synaptic vesicle and coated vesicle fractions isolated from rat brains. 13 97

Myosin-like protein was obtained from E. coli by extraction with a sucrose solution and by precipitation with rabbit skeletal actin. The preparation of E. coli myosin-like protein looked very similar, in the sodium dodecyl sulfate-gel electrophoretic pattern, to that of rabbit skeletal myosin. The myosin-like protein was able to reversibly bind to rabbit actin. It had the activities of EDTA-, Ca-, and Mg-ATPases. The product in the EDTA-ATPase reaction catalyzed by the myosin-like protein was identified as ADP by ion exchange chromatography. The Mg-ATPase activity of E. coli myosin-like protein was activated by either rabbit actin or E. coli actin-like protein though the activation was much stronger by the latter. However, the myosin-like protein did not exhibit superprecipitation either with rabbit actin or with E. coli actin-like protein. Actin-like protein was also obtained from E. coli by essentially the same procedures as those described for preparation of rabbit skeletal actin. E. coli actin-like protein was capable of activating Mg-ATPase of rabbit myosin, and also of superprecipitation with rabbit myosin. Extraction from both the whole cells and the membrane fraction of E. coli strongly suggested that the myosin-like protein and the actin-like protein are both localized in the membrane fraction rather than in the cytoplasmic fraction.
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PMID:Myosin-like protein and actin-like protein from Escherichia coli K12 C600. 14 24

A myosin-like protein was extracted and partially purified from a flowering plant, Egeria densa. It had no p-nitrophenyl phosphatase activity, but exhibited EDTA(K+)-ATPase [EC 3.6.1.3] activity at high ionic strength. Its molecular weight as estimated by gel filtration was 4-5 X 10(5). The presence of a heavy chain (MW = about 1.8 X 10(5)) was indicated by SDS-gel electrophoresis. Egeria myosin aggregated in an environment of low ionic strength and formed bipolar filaments. It bound with skeletal muscle F-actin with a periodicity of 40 nm.
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PMID:Identification of myosin in a flowering plant, Egeria densa. 15 12

A myosin-like protein was purified 40-fold from rat liver chromatin (as determined by the K+-EDTA-ATPase activity equal to 0.013 and 0.442 M PPi/mg.min for chromatin and purified protein, respectively). Electrophoresis performed under non-denaturating conditions revealed that the overall ATPase activity of the sample is associated with one component whose migration is very similar to that of skeletal muscle myosin. The myosin components isolated from the nuclei and cytoplasm of rat cardiac muscle differ by their electrophoretic mobilities; those from nuclei of different tissues, i.e., liver and heart, have similar mobilities.
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PMID:[Identification of myosin-like proteins included in chromatin]. 252 94

The proteins corresponding in molecular weight and solubility in salt solutions to skeletal muscle actin and myosin were revealed in liver and thymus chromatin fragments. When the ionic strength reached 0.3, about 60% of the myosin-like protein identified by electrophoretic mobility of high chains and the K+-EDTA-ATPase activity was cosedimented with nucleohistones. In the presence of ATP or PPi and Mg2+ the solubility of myosin in such salt solutions increased up to 90%, which was paralleled with significant stimulation of RNA release from the nucleohistones. The conformity in the degree of extraction and sedimentation of RNA and intranuclear myosin was also observed in other solutions used during myosin purification. The supposition that the nuclear system of contractile proteins causes labile, ATP-dependent binding of RNA to chromatin is discussed. No essential differences in the actin or myosin contents in the fractions of soluble and non-soluble chromatin were detected.
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PMID:[Contractile proteins in the fractions of soluble and insoluble chromatin of liver and thymus]. 614 Sep 58