| Calcium-induced desensitization of acetylcholine release from synaptosomes or proteoliposomes equipped with mediatophore, a presynaptic membrane protein. | |
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MedLine Citation:
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PMID: 2440993 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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A "fatigue" of acetylcholine (ACh) release is described in cholinergic synaptosomes stimulated with the calcium ionophore A23187 or gramicidin. A small conditioning calcium entry, which did not trigger a large ACh release, led to a decrease of transmitter release elicited by a second large calcium influx. This fatigue was half-maximal at approximately 30 microM external calcium and developed in a few minutes. In contrast, activation of release by calcium was very rapid and was half-maximal at approximately 0.5 mM external calcium. Activation and desensitization of release could be attributed to the recently identified presynaptic membrane protein, the "mediatophore." Proteoliposomes equipped with purified mediatophore showed a calcium-dependent activation and "fatigue" of ACh release similar to that of synaptosomes. It was found that the ionophore A23187 rapidly equilibrated internal and external calcium concentrations in proteoliposomes. Thus, the external calcium concentration gave the internal concentration required for activation or desensitization of proteoliposomal ACh release. The mediatophore showed remarkable calcium binding properties (20 sites/molecule) with a KD of 25 microM. The physiological implications of desensitization on the organization of release sites are discussed. |
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Authors:
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M Israël; F M Meunier; N Morel; B Lesbats |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of neurochemistry Volume: 49 ISSN: 0022-3042 ISO Abbreviation: J. Neurochem. Publication Date: 1987 Sep |
Date Detail:
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Created Date: 1987-09-23 Completed Date: 1987-09-23 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 2985190R Medline TA: J Neurochem Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 975-82 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acetylcholine
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metabolism* Animals Calcimycin / pharmacology Calcium / pharmacology* Electric Organ / cytology Gramicidin / pharmacology Kinetics Membrane Proteins / metabolism Nerve Tissue Proteins / metabolism* Proteolipids / metabolism* Synaptosomes / drug effects, metabolism* Torpedo |
| Chemical | |
Reg. No./Substance:
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0/Membrane Proteins; 0/Nerve Tissue Proteins; 0/Proteolipids; 0/mediatophore; 0/proteoliposomes; 1405-97-6/Gramicidin; 51-84-3/Acetylcholine; 52665-69-7/Calcimycin; 7440-70-2/Calcium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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