Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P20020 (adenosine triphosphatase)
 3,299 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To clarify the intracellular distribution of myosin in normal rat hepatocytes and its alterations in phal-loidin-treated rat hepatocytes as a morphologic basis for the dysfunction of microfilaments, we performed indirect immunofluorescence using monospecific antibody raised against rat hepatocyte myosin. Cryostat rat liver sections analyzed by the use of this antibody showed a characteristic polygonal staining pattern, indicating that myosin is localized close to the plasma membrane including the region of bile canaliculi. The observed myosin staining pattern of normal liver coincides with the pattern of actin distribution as demonstrated by double-staining on the same liver section with antimyosin antibody and rhodamine-phalloidin. Upon administration of phalloidin to rats, the following changes in the myosin staining pattern were observed. (a) Peripheral fluorescence along the plasma membrane, especially around the bile canaliculi and sinusoids, was greatly enhanced. (b) Numbers of small fluorescent dots appeared in the cytoplasm of hepatocytes. These changes in the localization of myosin are shown to overlap with those of actin filament distribution. Accompanying these changes of localization, cellular myosin content appears to be increased, as the myosin marker-enzyme NH4+(-)ethylenediaminetetraacetic acid-adenosine triphosphatase activity in hepatocyte extracts was elevated threefold after 7 days of phalloidin treatment. This increase of myosin may be due to the previously observed stabilizing effect on microfilaments of phalloidin against cellular proteases. Thus, phalloidin, which primarily alters actin filament distribution, induces the changes in myosin localization and the increase in cellular myosin content without causing dissociation of myosin from actin in the hepatocyte.
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PMID:Immunocytochemical localization of myosin in normal and phalloidin-treated rat hepatocytes. 267 10

Three well-characterized antimyosin heavy chain monoclonal antibodies (McAbs) were used as immunocytochemical reagents to study myosin isoform expression in relationship to adenosine triphosphatase (ATPase) defined fiber types in human muscle. The biopsy specimens were from patients with neurogenic muscle disease whose muscle exhibited fiber type grouping and group atrophy. The use of McAbs revealed heretofore unrecognized coexpression of multiple myosin isoforms in selected fibers in the pathologic samples which was not apparent with ATPase reactions and not present in normal muscle. The fibers containing multiple myosin isoforms were probably undergoing neurally directed fiber type transformation. Furthermore, a small population of fibers in neurogenic specimens expressed a "prenatal" myosin signifying the presence of regenerating fibers. We also demonstrated immunocytochemical evidence of the persistence of adult slow myosin in denervated mature human skeletal muscle despite the reputed necessity of innervation for maintenance of expression of this myosin isoform proffered by others.
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PMID:Coexpression of myosin isoforms in muscle of patients with neurogenic disease. 267 10

Fibers of the garter snake transversus abdominis muscle fall into three classes according to contraction speed: faster and slower twitch and tonic. To determine the relationship between these physiologically determined classes and established mammalian fiber types, individual fibers were assayed for key enzymes representing the major energy-generating pathways in vertebrate muscle. Five such enzymes were examined: lactate dehydrogenase, malate dehydrogenase, adenylokinase, fumarate hydratase, and beta-hydroxyacyl-CoA dehydrogenase. The muscle contained three principal metabolic fiber types. Fast-contracting twitch fibers had low-oxidative but high-glycolytic capacity and therefore resembled mammalian-type fast-twitch glycolytic (FG) fibers. Slower twitch fibers were high oxidative-high glycolytic, similar to mammalian-type fast-twitch, oxidative, glycolytic (FOG) fibers. Tonic fibers were high oxidative-low glycolytic; this metabolic profile is characteristic of type slow-twitch oxidative (SO) fibers in mammals. Activity of the enzyme adenylokinase, which in mammals correlates with contraction speed and myosin adenosine triphosphatase (ATPase) activity, separated these reptilian fibers into three groups that are similar but not identical to those delineated by oxidative and glycolytic enzymes. Adenylokinase and beta-hydroxyacyl-CoA dehydrogenase showed the widest range of activities in snake muscle and, therefore, the greatest ability to discriminate fiber types.
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PMID:Metabolic fiber types of snake transversus abdominis muscle. 273 94

Calcium-activated myosin adenosine triphosphatase (ATPase) activity has been measured in sections of rat ventricles that were rapidly frozen to preserve the structure and regulatory state of myosin occurring in vivo. These results were related to myosin isozyme composition measured in ventricles by native gel electrophoresis and by quantitative immunocytochemistry. Both total ATPase activity and percent alpha-heavy chain rapidly rise during the first month following birth. However, ATPase activity remains constant at a high level from 1 to 12 months following birth, even though percent alpha-heavy chain declines during this period. The ATPase activity of V1 myosin was specifically determined using sections in which V3 myosin had been completely inhibited by exposure to alkaline pH in the absence of adenosine 5'-triphosphate (ATP). Relative V1 specific activity, taken as the ratio of V1 ATPase activity to percent alpha-heavy chain, doubles in the first 2.0 months after birth and then remains approximately constant at this higher level until at least 4 months after birth. The specific activity of V1 can be further increased by the addition of adenosine-3',5'-cyclic monophosphate (cAMP). This effect of cAMP is age dependent, increasing threefold between 1 and 2 months following birth and then declining as V1 is replaced by V3.
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PMID:cAMP regulation of myosin ATPase activity in the maturing rat heart. 282 92

Previously, we have shown that okadaic acid (OA), isolated from black sponge (Halichondria okadai) causes contraction even in the absence of Ca++ in the saponin-permealized taenia isolated from guinea pig cecum. In the present study, mechanism of action of OA was examined using native actomyosin extracted from chicken gizzard smooth muscle. In the absence of Ca++, OA (0.1-1 microM) induced superprecipitation and increased the Mg++-adenosine triphosphatase activity. The OA-induced superprecipitation was enhanced by Ca++ at a concentration (greater than 0.1 microM) which did not activate the calmodulin-dependent myosin light chain (MLC) kinase. The effect of OA was not affected by the calmodulin inhibitor, trifluoperazine, at a concentration (100 microM) needed to inhibit the Ca++-induced response, but was inhibited markedly by the nonselective kinase inhibitors, amiloride (1 mM) and K-252a (5 microM). The OA-induced superprecipitation in the absence of Ca++ was accompanied by phosphorylation of the 20 K dalton MLC, which also was enhanced by low concentration of Ca++ (greater than 0.1 microM). OA did not change the phosphatase activity which dephosphorylates the phosphorylated MLC. An activator of Ca++- and phospholipid-dependent protein kinase, 12-O-tetradecanoylphorbol 13-acetate (1 microM), did not modulate superprecipitation or phosphorylation of MLC in the presence and absence of OA. Furthermore, inhibitors of Ca++ and phospholipid-dependent protein kinase, 1-(5-isoquinoline-sulfonyl)-2-methylpiperazine dihydrochloride (400 microM) and polymyxin B (100 micrograms/ml), affected neither superprecipitation nor phosphorylation of MLC induced by OA. With a reconstituted system containing purified myosin and MLC kinase, OA induced only slight phosphorylation of MLC.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Calcium-independent phosphorylation of smooth muscle myosin light chain by okadaic acid isolated from black sponge (Halichondria okadai). 282 58

New light microscopic visualization methods were developed for the histochemical detection of non-specific alkaline and acid phosphatase, Mg-, Ca- and Na, K-dependent adenosine triphosphatase, myosin adenosine triphosphatase, glucose-6-phosphatase, 5'-nucleotidase and thiamine pyrophosphatase with cerium ions as trapping agents in cryostat and plastic sections. The techniques are based on the conversion of cerium phosphate into cerium perhydroxide by H2O2 which decomposes at 55 degrees-60 degrees C into cerium hydroxide and oxygen radicals. These radicals are able to oxidize diaminobenzidine (DAB) to DAB brown. Addition of nickel ions to the DAB-H2O2 mixture generates bluish-black stained nickel-DAB complexes. Compared with the classical metal precipitation, azo, azoindoxyl and tetrazolium procedures the H2O2-DAB and especially the H2O2-DAB-nickel methods provided identical or superior results in catalytic phosphatase histochemistry and immunohistochemistry when using non-specific alkaline phosphatase as the enzyme label.
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PMID:The cerium perhydroxide-diaminobenzidine (Ce-H2O2-DAB) procedure. New methods for light microscopic phosphatase histochemistry and immunohistochemistry. 285 63

Native thin filaments were extracted from rabbit uterus by the procedure of Marston and Smith. The protein content was actin, tropomyosin, and caldesmon in molar ratios of 1:0.2:0.03. Some filamin, myosin, and calcium-binding protein were also present. The thin filaments activated skeletal or smooth muscle myosin magnesium adenosine triphosphatase at least 30-fold. Activation was regulated by Ca2+; maximum observed Ca2+ sensitivity was greater than 10 times. The thin filaments were dismantled into component proteins by the method of Smith and Marston. Actin and actin-tropomyosin-activated myosin magnesium adenosine triphosphatase, but the activation was not Ca2+-regulated. Added caldesmon inhibited adenosine triphosphatase activation by as much as 80%, with 50% inhibition at 1 caldesmon per 50 actin. Caldesmon inhibition was not Ca2+ dependent, but inhibition could be reversed by further addition of Ca2+ and calmodulin. It is concluded that the thin filaments of uterine smooth muscle are Ca2+ regulated and that this regulatory system could be involved in control of uterine smooth muscle contractility. A mechanism for thin filament regulation, mediated by caldesmon, is proposed.
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PMID:Calcium ion-dependent regulation of uterine smooth muscle thin filaments by caldesmon. 291 89

Using the histochemical reaction for myosin adenosine triphosphatase (ATPase), a study of the rat soleus muscle following tenotomy was undertaken. It was demonstrated that both type 2A and 2C fibers undergo degenerative changes following tenotomy. All previous studies have stated that only type 1 fibers were affected and developed central core lesions and that type 2 fibers were somehow protected from the degenerative process. The results of this experiment illustrate that central core lesions will develop in all three fiber types (types 1, 2A, and 2C) of the soleus following tenotomy.
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PMID:The development of central cores in both fiber types in tenotomized muscle. 293 36

Our results show that calcium activation of myofilament preparations of dog heart in the perinatal period is unaffected by a reduction in pH from 7.0 to 6.5, which, in adult heart myofilaments, induces a 0.4 pCa unit (-log molar free calcium concentration) rightward shift in the relation between pCa and myofibrillar adenosine triphosphatase activity. Acidic pH also had no effect on calcium binding to myofibrillar troponin C of perinatal hearts. The stoichiometry of troponin C bound calcium at full myofilament activation (about 3 mol calcium/mol troponin C) was the same for adult and perinatal heart myofibrils, as was their myofibrillar troponin C content. Moreover, there were no differences in isoelectric pH of troponin C from adult and perinatal hearts. We tested whether variants of myofilament proteins other than troponin C could account for the differential effects of acidic pH. In adult and perinatal dog heart preparations, myosin heavy chain isoenzymes appeared the same as measured, using native pyrophosphate gel electrophoresis. No evidence for thick filament-related calcium regulation in the perinatal heart myofilaments was obtained, when tested in studies in which native thin filaments were displaced with a 10-fold molar excess of pure actin. In preparations in which native thick filaments were displaced with a 10-fold molar excess of pure skeletal muscle myosin, the effects of acidic pH on calcium activation were the same as in native adult and perinatal preparations. Our major conclusion from these results in that the perinatal heart myofilaments are likely to possess variations in thin filament activity and structure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential effects of pH on calcium activation of myofilaments of adult and perinatal dog hearts. Evidence for developmental differences in thin filament regulation. 294 29

Extensor digitorum longus muscles of male adult White New Zealand rabbits were indirectly stimulated at 10 Hz for 12 h daily for periods ranging up to 28 days. After four weeks the stimulated muscles showed a nearly uniform profile of high succinate dehydrogenase activity and, when incubated after acid preincubation for myofibrillar adenosine triphosphatase, displayed more dark- and intermediate-staining fibers than their contralateral counterparts. Muscles stimulated from between 6 to 21 days revealed degenerative foci and phagocytosis of degenerated fibers. These fibers were mostly of the fast-twitch, glycolytic type. Small myofibers, which often contained central nuclei, and structures identified as myoblasts or myotubes, reacted with a monoclonal antibody prepared against embryonic myosin heavy chains. The data suggest that under the employed conditions the fast to slow conversion of chronically stimulated fast-twitch rabbit muscle is not exclusively caused by adult fiber transformation, but results in part from the substitution of fast-twitch glycolytic fibers with newly formed fibers that have a high oxidative profile.
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PMID:Degeneration-regeneration as a mechanism contributing to the fast to slow conversion of chronically stimulated fast-twitch rabbit muscle. 294 Nov 48


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