Source:http://linkedlifedata.com/resource/pubmed/id/10617655
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1
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| pubmed:dateCreated |
2000-1-31
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| pubmed:abstractText |
We determined the effect of nucleotides and protein kinase A (PKA) on the Ca(2+)-dependent gating of the cloned intermediate conductance, Ca(2+)-dependent K(+) channel, hIK1. In Xenopus oocytes, during two-electrode voltage-clamp, forskolin plus isobutylmethylxanthine induced a Ca(2+)-dependent increase in hIK1 activity. In excised inside-out patches, addition of ATP induced a Ca(2+)-dependent increase in hIK1 activity (NP(o)). In contrast, neither nonhydrolyzable (AMP-PNP, AMP-PCP) nor hydrolyzable ATP analogs (GTP, CTP, UTP, and ITP) activated hIK1. The ATP-dependent activation of hIK1 required Mg(2+) and was reversed by either exogenous alkaline phosphatase or the PKA inhibitor PKI(5-24). The Ca(2+) dependence of hIK1 activation was best fit with a stimulatory constant (K(s)) of 350 nM and a Hill coefficient (n) of 2.3. ATP increased NP(o) at [Ca(2+)] >100 nM while having no effect on K(s) or n. Mutation of the single PKA consensus phosphorylation site at serine 334 to alanine (S334A) had no effect on the PKA-dependent activation during either two-electrode voltage-clamp or in excised inside-out patches. When expressed in HEK293 cells, ATP activated hIK1 in a Mg(2+)-dependent fashion, being reversed by alkaline phosphatase. Neither PKI(5-24) nor CaMKII(281-309) or PKC(19-31) affected the ATP-dependent activation. Northern blot analysis revealed hIK1 expression in the T84 colonic cell line. Endogenous hIK1 was activated by ATP in a Mg(2+)- and PKI(5-24)-dependent fashion and was reversed by alkaline phosphatase, whereas CaMKII(281-309) and PKC(19-31) had no effect on the ATP-dependent activation. The Ca(2+)-dependent activation (K(s) and n) was unaffected by ATP. In conclusion, hIK1 is activated by a membrane delimited PKA when endogenously expressed. Although the oocyte expression system recapitulates this regulation, expression in HEK293 cells does not. The effect of PKA on hIK1 gating is Ca(2+)-dependent and occurs via an increase in NP(o) without an effect on either Ca(2+) affinity or apparent cooperativity.
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| pubmed:grant | |
| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/1-Methyl-3-isobutylxanthine,
http://linkedlifedata.com/resource/pubmed/chemical/Adenosine Triphosphate,
http://linkedlifedata.com/resource/pubmed/chemical/Alkaline Phosphatase,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Cyclic AMP,
http://linkedlifedata.com/resource/pubmed/chemical/Cyclic AMP-Dependent Protein Kinases,
http://linkedlifedata.com/resource/pubmed/chemical/Forskolin,
http://linkedlifedata.com/resource/pubmed/chemical/Intermediate-Conductance...,
http://linkedlifedata.com/resource/pubmed/chemical/Ionomycin,
http://linkedlifedata.com/resource/pubmed/chemical/Ionophores,
http://linkedlifedata.com/resource/pubmed/chemical/Peptide Fragments,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium Channels...
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| pubmed:status |
MEDLINE
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| pubmed:month |
Jan
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| pubmed:issn |
0021-9258
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:day |
7
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| pubmed:volume |
275
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
585-98
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| pubmed:dateRevised |
2007-11-15
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| pubmed:meshHeading |
pubmed-meshheading:10617655-1-Methyl-3-isobutylxanthine,
pubmed-meshheading:10617655-Adenosine Triphosphate,
pubmed-meshheading:10617655-Alkaline Phosphatase,
pubmed-meshheading:10617655-Animals,
pubmed-meshheading:10617655-Biological Transport,
pubmed-meshheading:10617655-Calcium,
pubmed-meshheading:10617655-Calcium Signaling,
pubmed-meshheading:10617655-Cell Membrane,
pubmed-meshheading:10617655-Cyclic AMP,
pubmed-meshheading:10617655-Cyclic AMP-Dependent Protein Kinases,
pubmed-meshheading:10617655-Electric Conductivity,
pubmed-meshheading:10617655-Epithelial Cells,
pubmed-meshheading:10617655-Forskolin,
pubmed-meshheading:10617655-Intermediate-Conductance Calcium-Activated Potassium...,
pubmed-meshheading:10617655-Ion Channel Gating,
pubmed-meshheading:10617655-Ionomycin,
pubmed-meshheading:10617655-Ionophores,
pubmed-meshheading:10617655-Oocytes,
pubmed-meshheading:10617655-Patch-Clamp Techniques,
pubmed-meshheading:10617655-Peptide Fragments,
pubmed-meshheading:10617655-Phosphorylation,
pubmed-meshheading:10617655-Potassium Channels,
pubmed-meshheading:10617655-Potassium Channels, Calcium-Activated,
pubmed-meshheading:10617655-Xenopus
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| pubmed:year |
2000
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| pubmed:articleTitle |
Kinase-dependent regulation of the intermediate conductance, calcium-dependent potassium channel, hIK1.
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| pubmed:affiliation |
Department of Cell Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
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| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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