Source:http://linkedlifedata.com/resource/pubmed/id/12586831
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
18
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pubmed:dateCreated |
2003-4-28
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pubmed:abstractText |
Maurocalcine (MCa) isolated from Scorpio maurus palmatus venom shares 82% sequence identity with imperatoxin A. Both scorpion toxins are putative mimics of the II-III loop peptide (termed peptide A (pA)) of alpha(1s)-dihydropyridine receptor and are thought to act at a common site on ryanodine receptor type 1 (RyR1) important for skeletal muscle EC coupling. The relationship between the actions of synthetic MCa (sMCa) and pA on RyR1 were examined. sMCa released Ca(2+) from SR vesicles (EC(50) = 17.5 nm) in a manner inhibited by micromolar ryanodine or ruthenium red. pA (0.5-40 microm) failed to induce SR Ca(2+) release. Rather, pA enhanced Ca(2+) loading into SR and fully inhibited Ca(2+)-, caffeine-, and sMCa-induced Ca(2+) release. The two peptides modified single channel gating behavior in distinct ways. With Cs(+)-carrying current, 10 nm to 1 microm sMCa induced long lived subconductances having 48% of the characteristic full open state and occasional transitions to 29% at either positive or negative holding potentials. In contrast, pA stabilized long lived channel closures with occasional burst transitions to 65% (s1) and 86% (s2) of the full conductance. The actions of pA and sMCa were observed in tandem. sMCa stabilized additional subconductance states proportional to pA-induced subconductances (i.e. 43% of pA-modified s1 and s2 substates), revealing a proportional gating mechanism. [(3)H]Ryanodine binding and surface plasmon resonance analyses indicated that the peptides did not interact by simple competition for a single class of mutually exclusive sites on RyR1 to produce proportional gating. The actions of sMCa were also observed with ryanodine-modified channels and channels deficient in immunophilin 12-kDa FK506-binding protein. These results provide evidence that sMCa and pA stabilize distinct RyR1 channel states through distinct mechanisms that allosterically stabilize gating states having proportional conductance.
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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/Caffeine,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Oncogene Protein pp60(v-src),
http://linkedlifedata.com/resource/pubmed/chemical/Peptide Fragments,
http://linkedlifedata.com/resource/pubmed/chemical/Ryanodine,
http://linkedlifedata.com/resource/pubmed/chemical/Ryanodine Receptor Calcium Release...,
http://linkedlifedata.com/resource/pubmed/chemical/Scorpion Venoms,
http://linkedlifedata.com/resource/pubmed/chemical/maurocalcine,
http://linkedlifedata.com/resource/pubmed/chemical/peptide A
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pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
2
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pubmed:volume |
278
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
16095-106
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pubmed:dateRevised |
2009-11-19
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pubmed:meshHeading |
pubmed-meshheading:12586831-Amino Acid Sequence,
pubmed-meshheading:12586831-Animals,
pubmed-meshheading:12586831-Caffeine,
pubmed-meshheading:12586831-Calcium,
pubmed-meshheading:12586831-Ion Channel Gating,
pubmed-meshheading:12586831-Molecular Sequence Data,
pubmed-meshheading:12586831-Oncogene Protein pp60(v-src),
pubmed-meshheading:12586831-Peptide Fragments,
pubmed-meshheading:12586831-Rabbits,
pubmed-meshheading:12586831-Ryanodine,
pubmed-meshheading:12586831-Ryanodine Receptor Calcium Release Channel,
pubmed-meshheading:12586831-Sarcoplasmic Reticulum,
pubmed-meshheading:12586831-Scorpion Venoms
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pubmed:year |
2003
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pubmed:articleTitle |
Maurocalcine and peptide A stabilize distinct subconductance states of ryanodine receptor type 1, revealing a proportional gating mechanism.
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pubmed:affiliation |
Department of Molecular Biosciences and Graduate Program in Neurosciences, University of California, Davis, CA 95616, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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