Abstract |
Using a combination of fluorescence measurements of intracellular Ca(2+) ion concentration ([Ca(2+)](i)) and membrane potential we have investigated the sensitivity to serine/threonine phosphatase inhibition of Ca(2+) entry stimulated by activation of the Ca(2+) release-activated Ca(2+) (CRAC) entry pathway in rat basophilic leukemia cells. In both suspension and adherent cells, addition of the type 1/2A phosphatase inhibitor calyculin A, during activation of CRAC uptake, resulted in a fall in [Ca(2+)](i) to near preactivation levels. Pre-treatment with calyculin A abolished the component of the Ca(2+) rise associated with activation of CRAC uptake and inhibited Mn(2+) entry, consistent with a requirement of phosphatase activity for activation of the pathway. Depletion of intracellular Ca(2+) stores is accompanied by a large depolarisation which is absolutely dependent upon Ca(2+) entry via the CRAC uptake pathway. Application of calyculin A or okadaic acid, a structurally unrelated phosphatase antagonist inhibits this depolarisation. Taken in concert, these data demonstrate a marked sensitivity of the CRAC entry pathway to inhibition by calyculin A and okadaic acid.
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Authors | Nicholas E Evans, Mark K L Forth, Anna K Simpson, Michael J Mason |
Journal | Biochimica et biophysica acta
(Biochim Biophys Acta)
Vol. 1718
Issue 1-2
Pg. 32-43
(Dec 10 2005)
ISSN: 0006-3002 [Print] Netherlands |
PMID | 16297373
(Publication Type: Journal Article)
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Chemical References |
- Boron Compounds
- Cations, Divalent
- Enzyme Inhibitors
- Marine Toxins
- Oxazoles
- Okadaic Acid
- Manganese
- Thapsigargin
- calyculin A
- 2-aminoethoxydiphenyl borate
- Phosphoprotein Phosphatases
- Protein Phosphatase 1
- Calcium
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Topics |
- Animals
- Boron Compounds
(pharmacology)
- Calcium
(metabolism)
- Calcium Signaling
(drug effects)
- Cations, Divalent
(metabolism)
- Cells, Cultured
- Enzyme Inhibitors
(pharmacology)
- Ion Transport
(drug effects)
- Leukemia, Basophilic, Acute
- Manganese
(metabolism)
- Marine Toxins
- Membrane Potentials
(drug effects)
- Okadaic Acid
(pharmacology)
- Oxazoles
(pharmacology)
- Phosphoprotein Phosphatases
(antagonists & inhibitors)
- Protein Phosphatase 1
- Rats
- Thapsigargin
(pharmacology)
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