Ectonucleotidases of Avian Gizzard Smooth Muscle and Liver Plasma Membranes: A Comparative Study

Caldwell, Charles C.; Davis, Michael D.; Knowles, Aileen F.

doi:10.1006/abbi.1998.1008

Cited by 35 publications

(44 citation statements)

References 52 publications

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“…Table 3 shows that: (a) in the absence of NP-40, the ATP hydrolysis activities were similar at pH 7.4 and 6.4, whereas ADP hydrolysis activity at pH 6.4 was threefold greater than at pH 7. both ATPase and ADPase activities were inhibited by 10 mM azide, but ADPase activity was more sensitive to azide inhibition than ATP hydrolysis and inhibition in general was greater at pH 6.4 than at pH 7.4. These characteristics are similar to those displayed by the enzyme in its native membranes [23] and the purified enzyme described above. Figure 6 shows that MC18 detected protein bands of molecular masses of 80-85 kDa in HeLa cells expressing the chicken ecto-ATPDase but not in HeLa cells transfected with the pcDNA3 vector alone.…”

Section: Expression Of the Chicken Liver Ecto-atpdase Cdnasupporting

confidence: 80%

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Purification, characterization, cloning, and expression of the chicken liver ecto‐ATP‐diphosphohydrolase

Knowles

Nagy

Strobel

et al. 2002

European Journal of Biochemistry

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We previously demonstrated that the major ecto‐nucleoside triphosphate phosphohydrolase in the chicken liver membranes is an ecto‐ATP‐diphosphohydrolase (ecto‐ ATPDase) [Caldwell, C., Davis, M.D. & Knowles, A.F. (1999) Arch. Biochem. Biophys. 362, 46–58]. Enzymatic properties of the liver membrane ecto‐ATPDase are similar to those of the chicken oviduct ecto‐ATPDase that we have previously purified and cloned. Using antibody developed against the latter, we have purified the chicken liver ecto‐ATPDase to homogeneity. The purified enzyme is a glycoprotein with a molecular mass of 85 kDa and a specific activity of ≈ 1000 U·mg protein−1. Although slightly larger than the 80‐kDa oviduct enzyme, the two ecto‐ATPDases are nearly identical with respect to their enzymatic properties and mass of the deglycosylated proteins. The primary sequence of the liver ecto‐ATPDase deduced from its cDNA obtained by RT‐PCR cloning also shows only minor differences from that of the oviduct ecto‐ATPDase. Immunochemical staining demonstrates the distribution of the ecto‐ATPDase in the bile canaliculi of the chicken liver. HeLa cells transfected with the chicken liver ecto‐ATPDase cDNA express an ecto‐nucleotidase activity with characteristics similar to the enzyme in its native membranes, most significant of these is stimulation of the ATPDase activity by detergents, which inhibits other members of the ecto‐ nucleoside triphosphate diphosphohydrolase (E‐NTPDase) family. The stimulation of the expressed liver ecto‐ATPDase by detergents indicates that this property is intrinsic to the enzyme protein, and cannot be attributed to the lipid environment of the native membranes. The molecular identification and expression of a liver ecto‐ATPDase, reported here for the first time, will facilitate future investigations into the differences between structure and function of the different E‐NTPDases, existence of liver ecto‐ATPDase isoforms in different species, its alteration in pathogenic conditions, and its physiological function.

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Section: Expression Of the Chicken Liver Ecto-atpdase Cdnasupporting

confidence: 80%

“…An ecto-ATPDase similar to the chicken oviduct enzyme is present in the chicken liver membranes [23]. We report here the complete purification of the chicken liver ecto-ATPDase, its enzymatic properties and localization, cloning of the full-length cDNA and its expression.…”

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confidence: 95%

Purification, characterization, cloning, and expression of the chicken liver ecto‐ATP‐diphosphohydrolase

Knowles

Nagy

Strobel

et al. 2002

European Journal of Biochemistry

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“…The hydrolysis of GTP demonstrated the presence of an ecto-ATPase. Ecto-ATPase degrades both ATP and GTP (Barry, 1992;Caldwell et al, 1999). The hydroly-sis of GTP was only 83% of ATP hydrolysed, hence the difference with the hydrolysis of ATP was 17%, which agrees with the percentage of Ca-pump estimated to be in the membrane fraction (14-20%).…”

Section: Ca Atpase Activitysupporting

confidence: 77%

Detection and Localization of a Ca2+-ATPase Activity in Toxoplasma gondii.

Bouchot

Jaillet

Bonhomme

et al. 2001

Cell Struct. Funct.

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ABSTRACT. Toxoplasma gondii, the agent causing toxoplasmosis, is an obligate intracellular protozoan parasite.A calcium signal appears to be essential for intracellular transduction during the active process of host cell invasion. We have looked for a Ca 2+ -transport ATPase in tachyzoites and found Ca 2+ -ATPase activity (11-22 nmol Pi liberated/mg protein/min) in the tachyzoite membrane fraction. This ATP-dependent activity was stimulated by Ca 2+ and Mg 2+ ions and by calmodulin, and was inhibited by pump inhibitors (sodium orthovanadate or thapsigargin). We used cytochemistry and X-ray microanalysis of cerium phosphate precipitates and immunolabelling to find the Ca 2+ , Mg 2+ -ATPase. It was located mainly in the membrane complex, the conoid, nucleus, secretory organelles (rhoptries, dense granules) and in vesicles with a high calcium concentration. Thus, Toxoplasma gondii possesses Ca 2+ -pump ATPase (Ca 2+ , Mg 2+ -ATPase) as do eukaryotic cells.

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“…The ectonucleotidases have been shown to be present in a variety of tissues, and it has also been shown that these enzymes can hydrolyse purine and pyrimidine diand triphosphates other than ATP (Ziganshin et al, 1995a;Zimmermann, 1996;Caldwell et al, 1999). After its release into the synapse, ATP is sequentially broken down to ADP and AMP by the ecto-ATPase and ectonucleotidases and finally to adenosine by the 5V-nucleotidase (Zimmermann et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

“…Ecto-ATPase activity has been shown to be present in many tissues and cell types ranging from blood cells to neurons (Crack et al, 1995;Caldwell et al, 1999;Dunn et al, 2001;Liang et al, 2000;Meghji and Burnstock, 1995;Zinchuk et al, 1999a,b). At synapses, ecto-ATPase is thought to hydrolyse the neuronally released ATP, degrading it into ADP and inorganic phosphate (Pi).…”

Section: Introductionmentioning

confidence: 99%

Effects of cooling and ARL 67156 on synaptic ecto-ATPase activity in guinea pig and mouse vas deferens

Ghildyal

Manchanda

2004

Autonomic Neuroscience

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Ectonucleotidases of Avian Gizzard Smooth Muscle and Liver Plasma Membranes: A Comparative Study

Cited by 35 publications

References 52 publications

Purification, characterization, cloning, and expression of the chicken liver ecto‐ATP‐diphosphohydrolase

Purification, characterization, cloning, and expression of the chicken liver ecto‐ATP‐diphosphohydrolase

Detection and Localization of a Ca2+-ATPase Activity in Toxoplasma gondii.

Effects of cooling and ARL 67156 on synaptic ecto-ATPase activity in guinea pig and mouse vas deferens

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