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)

Protein kinase activity was determined in subcellular fractions of rat testis interstitial tissue after incubation of the intact tissue with LH (luteinizing hormone) in vitro. Various factors that might have changed the activity of this enzyme during preparation of the fractions before assay were also investigated. The following results were obtained. 1. LH and 3-isobutyl-1-methylxanthine (a phosphodiesterase inhibitor) added together during incubation of the interstitial tissue caused a twofold increase in the protein kinase activity in the total tissue homogenate and subcellular fractions (12000g X 5 min pellet and 105000g X 60 min supernatant and pellet). 2. A decrease of approx. 40% in the total amount of protein kinase recovered in the soluble fraction (105000g supernatant) occurred in tissue incubated with LH and 3-isobutyl-1-methylxanthine when compared with the controls. No change in total activity was found in the other fractions. 3. LH and 3-isobutyl-1-methylxanthine caused an increase in cyclic AMP concentration in the soluble fraction (from 30 +/- 6 to 450 +/- 40 pmol/mg of protein, means +/- S.E.M., n = 4), but there was little or no increase in the particulate fractions [from 9 +/- 1 to 13 +/- 3 pmol/mg of protein (n = 3) and from 6 +/- 2 to 23 +/- 11 pmol/mg of protein (n = 3) in the 12000g and 105000g pellets respectively]. 4 Addition of 3-isobutyl-1-methylxanthine alone had little effect on protein kinase activity or cyclic AMP concentrations. 5. Little or no protein kinase activity could be demonstrated in subcellular particulate fractions unless Triton X-100 was added; the effect of this detergent was shown to be at least partly due to the inhibition of adenosine triphosphatase activity. 6. In the presence of Triton X-100 approx. 57% of the total protein kinase activity in the homogenate was found in the 105000g supernatant compared with 11% in the 105000g pellet and 32% in the 12000g pellet. 7. In contrast with adipose-tissue protein kinase [Corbin et al. (1973) J. Biol. Chem. 248, 1813-1821] the relative amounts of cyclic AMP-dependent and -dependent enzyme were not affected by dilution of the interstitial-tissue fractions. NaCl (0.5 M) decreased the estimated total amount of protein kinase activity.
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PMID:Protein kinase activity in rat testis interstitial tissue. Effect of luteinizing hormone and other factors. 18 Sep 76

The purpose of this study was to try to differentiate histochemically between the various enzymes which may catalyze the hydrolysis of ATP in developing rat dental tissues. Freeze cut and freeze dried sections of molar and incisor teeth were incubated in lead capture-based media at pH 5.0, 7.2 or 9.4 with one of the following substrates: beta-glycerophosphate, AMP, ADP, ATP, AMP-PNP and tetrasodium pyrophosphate. To establish the enzymatic nature of the hydrolysis parallel sections were incubated after prior fixation in either formaldehyde or glutaraldehyde. By comparing the enzymatic stainings obtained with the various substrates and at the different pH:s, it was concluded that ATP can be visibly hydrolyzed in rat dental tissues by alkaline phosphatase (stratum intermedium, apical part of maturation ameloblasts, basal part of all ameloblasts, odontoblasts and subodontoblastic layer), specific ATPase (apical and basal parts of secretory ameloblasts) and ATP pyrophosphatase and/or adenylate cyclase (stratum intermedium, odontoblasts). Acid phosphatase, specific ADPase, 5'-nucleotidase, inorganic pyrophosphatase, 3':5'-cyclic-AMP-phosphodiesterase and adenylate kinase on the other hand, seem not to be engaged in the ATP hydrolysis to such a degree as to complicate the interpretation of the histochemical staining. The alkaline phosphatase part of the ATP hydrolysis appeared to be rather insensitive to aldehyde fixation, while the hydrolysis effected by specific ATPase and ATP pyrophosphatase and/or adenylate cyclase was extinguished after fixation with formaldehyde for 4 h or glutaraldehyde for 10 min.
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PMID:Adenosine triphosphate hydrolysis in rat dental tissues. A histochemical study to differentiate the enzymes involved. 18 60

Phosphodiesterase activator protein and troponin-C have been purified from rat testis and rabbit skeletal muscle, respectively. The two proteins appear to be structurally distinct since the activator protein migrates faster than troponin-C on sodium dodecyl sulfate-polyacrylamide gels. Each of the calcium-binding proteins will, however, substitute for the other in their respective biological systems. Testis activator protein forms a complex with rabbit muscle troponin subunits TnI and TnT soluble in low salt. This hybrid complex (AIT) can regulate rabbit skeletal muscle actomyosin ATPase activity. AIT regulation, although influenced by free Aa2+ levels, is distinct from that of native troponin. Likewise, muscle troponin-C can substitute for activator protein in the stimulation of cyclic nucleotide phosphodiesterase. Troponin-C will fully stimulate phosphodiesterase although its affinity is 600-fold lower than that of activator protein. Ca2+ regulation studies demonstrate that both proteins require micormolar levels of free Ca2+ to induce phosphodiesterase activation. Activator protein requires 1.2 x 10(6) M and troponin-C, 1.9 X 10(6) M free Ca2+ for half-maximal stimulation of phosphodiesterase. The biological cross-reactivity of these proteins supports the sequence homology recently reported by Watterson et al. (Watterson, D.M., Harrelson, W.G., Keller, P.M., Sharief, F., and Vanaman, T.C. (1976) J.Biol. Chem. 251, 4501-4513). In addition, this preliminary study suggests that this nonmuscle troponin-C-like protein potentially may function in other Ca2+-regulated cellular events in addition to its moculation of cyclic nucleotide levels.
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PMID:Biological cross-reactivity of rat testis phosphodiesterase activator protein and rabbit skeletal muscle troponin-C. 19 60

Cell division is induced in stationary cultures of BALB/c-3T3 mouse embryo cells without renewal of medium by addition of the tumor promoter, phorbol myristate acetate (PMA), or bovine serum. The addition of dbcAMP (10(-3) M) or other inhibitors of cAMP phosphodiesterase, papaverine (6.7 X 10(-6) M), Persantin (5 X 10(-5) M) or RO-20-1724 (10(-4) M), prevents cell replication induced by PMA or serum. In contrast, ouabain (10(-4) M) and N,N'-dicyclohexylcarbodiimide (10(-5) M), inhibitors of Na+-K+-ATPase activity, block the PMA-stimulated effect but do not inhibit serum-stimulated cell division. Several stages in the cell cycle are sensitive to dbcAMP addition. One is early in the G1 phase at the time of reinitiation of the cell cycle from a stationary (Go) phase, a second is associated with the G1-S transition, and a third with passage of cells from a post-S phase to mitosis. Based on observations of early morphological changes, responses of plasma membrane enzymes and effects of enzyme inhibitors, the stimulation of cell division in BALB/c-3T3 cells by PMA or serum appears to involve several membrane functions which may act in a cooperative manner.
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PMID:Induction of cell division in BALB/c-3T3 cells by phorbol myristate acetate or bovine serum: effects of inhibitors of cyclic AMP phosphodiesterase and Na+-K+-ATPase. 19 94

From a homogenate of rabbit colon muscle two ATP dependent Ca-accumulating microsomal fractions were isolated by differential centrifugation on a sucrose density grandient at 35% and 35-45% sucrose. Adenylate cyclase and phosphodiesterase activities were found in the fractions. The Ca-accumulation and the ATPase activity of these fractions were stimulated by cyclic AMP (10(-5)M) at an ATP concentration of 0.35 mM ATP. In the presence of higher concentrations of ATP (5 mM) cyclic AMP had no effect on the Ca-binding. The higher concentration of ATP markedly increased the cyclic AMP formation in relation to the activity found at the lower concentration of ATP. Isoprenaline (2 X 10(-6)M) stimulated the Ca-accumulation in the 35-45% fraction and increased the hydrolysis of ATP. These effects were absent in the fraction isolated at 35% sucrose. In the former fraction isoprenaline also stimulated the adenylate cyclase activity at 0.35 mM but not at 5 mM ATP. Both the effect of isoprenaline on the Ca-binding and the adenylate cyclase activity were inhibited by the adrenergic beta-receptor blocking agent sotalol. In the 35-45% fraction papaverine (1 X 10(-3)M) stimulated the Ca-accumulation and inhibited the phosphodiesterase activity. It is suggested that cyclic AMP and agents which influence the cyclic AMP metabolism in the microsomes may have a regulatory role on the Ca-binding of the microsomes.
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PMID:Cyclic AMP and Ca-binding in microsomal fractions isolated from rabbit colon smooth muscle. 19 87

Chlorpropamide and phenformin inhibited (Na+ - K+)-ATPase and stimulated a high affinity cyclic AMP-phosphodiesterase of isolated liver plasma membrane when tested in vitro. In addition, the two drugs decreased the intracellular cyclic AMP content of isolated hepatocytes without being effective on plasma membrane-bound adenylate cyclase. The results suggest that the plasma membrane plays an important role in the mechanism of action of the two hypoglycemic drugs, but do not exclude the presence of intracellular targets.
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PMID:Effect of chlorpropamide and phenformin on rat liver: the effect on plasma membrane-bound enzymes and cyclic AMP content of hepatocytes in vitro. 20 70

Substances known to alter cyclic nucleotide levels in cells were applied to the isolated toad retina and effects on rod electrical and adaptive behavior were studied. The retina was continually superfused in control ringer's or ringer's containing one or a combination of drugs, and rod activity was recorded intracellularly. Superfusion with cGMP, Bu(2)GMP, isobutylmethylxanthine (IBMX; a phosphodiesterase inhibitor), or PGF(2alpha) (a prostaglandin) caused effects in rods that closely match those observed when extracellular Ca(2+) levels were lowered. For example, short exposures (up to 6 min) of the retina to these substances caused depolarization of the membrane potential, increase in response amplitudes, and some changes in waveform; but under dark-adapted or partially light-adapted conditions receptor sensitivity was virtually unaffected. That is, the position of the V-log I curve on the intensity axis was determined by the prevailing light level, not by drug level. These drugs, like lowered extracellular Ca(2+), also decreased the period of receptor saturation after a bright-adapting flash, resulting in an acceleration of the onset of membrane and sensitivity recovery during dark adaptation. Long-term (6-15 min) exposure of a dark-adapted retina to 5 mM IBMX or a combination of IBMX and cGMP caused a loss of response amplitude and a desensitization of the rods that was similar to that observed in rods after a long-term low Ca(2+) (10(-9)M) treatment. Application of high (3.2 mM) Ca(2+) to the retina blocked the effects of applied Bu(2)cGMP. PGE(1) superfusion mimicked the effects of increasing extracellular Ca(2+). The results show that increased cGMP and lowered Ca(2+) produce similar alterations in the electrical activity of rods. These findings suggest that Ca(2+) and cGMP are interrelated messengers. We speculate that low Ca(2+) may lead to increased intracellular cGMP, and/or that applied cGMP, and/or that applied cGMP may lower cytosol Ca(2+), perhaps by stimulating Ca(2+)- ATPase pumps in the outer segment.
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PMID:Electrical and adaptive properties of rod photoreceptors in Bufo marinus. II. Effects of cyclic nucleotides and prostaglandins. 20 24

From a homogenate of rabbit colon muscle subcellular fractions were isolated by differential centrifugation. The crude microsomal fraction could be separated into subfractions, a fraction of vesicular microsomes at 35% sucrose, a fraction containing sarcolemma, mitochondrial fragments and microsomal vesicles at 35--45% sucrose and a small protein fraction at 45--55% sucrose. Their biochemical properties and their morphological characterization were investigated. The cholesterol and the phospholipid content was equally distributed between the microsomal fractions 35% and 35--45% while the RNA was localized to the mitochondria and the microsomal fraction 35%. The enzyme cytochrome c oxidase was found to be concentrated in the mitochondria while a high contamination was found in the microsomal fractions 35--45%. The NADH-oxidase activity was highest in the 35% fraction and the 5'-nucleotidase activity in the 40,000 X g supernatant. The microsomal subfractions contained the enzymes ATPase, adenylate cyclase and phosphodiesterase. In the 35% fraction Ca stimulated the hydrolysis of ATP. The binding of [3H]-ouabain and the incorporation of [3H]-leucine was most pronounced in the 35% fraction. In a K+-free Krebs Ringer medium the binding of the glucoside was stimulated in all the fractions. From these results we concluded that the fraction 35% sucrose may be mainly derived from the endoplasmic reticulum and the plasma membrane while the 35--45% originates from the plasma membrane, mitochondria and to a lesser extent the endoplasmic reticulum.
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PMID:Biochemical and morphological characterization of subcellular fractions isolated from rabbit colon muscle. 20 90

The recently discovered heat-stable inhibitor protein of the Ca2+-activated cyclic nucleotide phosphodiesterase (Sharma, R. K., Wirch, E. & Warg, J. H. (1978) J. Biol. Chem., in press) has been purified 238 214-fold from bovine brain extract using an affinity column of the modulator protein--Sepharose 4B conjugate. The purified sample appears to be homogeneous as judged by sodium dodecyl sulphate (SDS) gel electrophoresis. The protein band has a mobility corresponding to that of a polypeptide of molecular weight 68 000. Since the heat-stable inhibitor protein has a molecular weight of 70 000 under nondenaturing conditions, it suggests that it is a monomeric protein. The protein has no inhibitory activity toward the cAMP-dependent protein kinase or protein phosphatase. The purified sample has been tested for various enzyme activities which include ATPase, GTPase, cAMP phosphodiesterase, cGMP phosphodiesterase, 5'-nucleotidase, and protein kinase. None of these activities are exhibited by the purified sample.
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PMID:Purification of the heat-stable inhibitor protein of the Ca2+-activated cyclic nucleotide phosphodiesterase by affinity chromatography. 20 31

Changes in the content of cyclic nucleotides (cAMP and cGMP) and related enzyme activities were observed in the rat thyroid, pituitary and plasma during the prolonged increase of endogenous TSH produced by treatment with methylthiouracil (MTU). Experiments were performed after 4 weeks treatment with MTU. The wet weight and cAMP content per wet weight of the thyroid increased 3 and 1.4 times respectively, but cGMP showed a slight decrease. Pituitary weight increased 1.3 times, but cAMP and cGMP content did not change. The cAMP level in plasma also increased about 1.3 times, but cGMP did not increase. The cAMP-phosphodiesterase activity in the thyroid, pituitary and plasma was increased 1.9, 1.4 and 1.3 times respectively after MTU treatment, while cGMP-phosphodiesterase showed no significant change. ATPase activity in the thyroid and pituitary was also increased more than 1.5 times after MTU treatment, while 5'-nucleotidase activitity decreased remarkably. These data indicate that the metabolism of the cyclic nucleotide system in the thyroid is stimulated by TSH.
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PMID:Changes in the cyclic nucleotides of rat thyroid, pituitary and plasma caused by methylthiouracil treatment. 21 61


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