{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T17:30:16Z","timestamp":1791307816682,"version":"4.3.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"24","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1992,12,15]]},"abstract":"<jats:p>We report the purification of two peptides, called \"imperatoxin inhibitor\" and \"imperatoxin activator,\" from the venom of the scorpion Pandinus imperator targeted against ryanodine receptor Ca(2+)-release channels. Imperatoxin inhibitor has a M(r) of approximately 10,500, inhibits [3H]ryanodine binding to skeletal and cardiac sarcoplasmic reticulum with an ED50 of approximately 10 nM, and blocks openings of skeletal and cardiac Ca(2+)-release channels incorporated into planar bilayers. In whole-cell recordings of cardiac myocytes, imperatoxin inhibitor decreased twitch amplitude and intracellular Ca2+ transients, suggesting a selective blockade of Ca2+ release from the sarcoplasmic reticulum. Imperatoxin activator has a M(r) of approximately 8700, stimulates [3H]ryanodine binding in skeletal but not cardiac sarcoplasmic reticulum with an ED50 of approximately 6 nM, and activates skeletal but not cardiac Ca(2+)-release channels. These ligands may serve to selectively \"turn on\" or \"turn off\" ryanodine receptors in fragmented systems and whole cells.<\/jats:p>","DOI":"10.1073\/pnas.89.24.12185","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T08:14:57Z","timestamp":1149063297000},"page":"12185-12189","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":116,"title":["Scorpion toxins targeted against the sarcoplasmic reticulum Ca(2+)-release channel of skeletal and cardiac muscle."],"prefix":"10.1073","volume":"89","author":[{"given":"H H","family":"Valdivia","sequence":"first","affiliation":[{"name":"Department of Physiology, University of Wisconsin School of Medicine, Madison 53706."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M S","family":"Kirby","sequence":"additional","affiliation":[{"name":"Department of Physiology, University of Wisconsin School of Medicine, Madison 53706."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"W J","family":"Lederer","sequence":"additional","affiliation":[{"name":"Department of Physiology, University of Wisconsin School of Medicine, Madison 53706."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R","family":"Coronado","sequence":"additional","affiliation":[{"name":"Department of Physiology, University of Wisconsin School of Medicine, Madison 53706."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1992,12,15]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.89.24.12185","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T13:33:30Z","timestamp":1649856810000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.89.24.12185"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1992,12,15]]},"references-count":0,"journal-issue":{"issue":"24","published-print":{"date-parts":[[1992,12,15]]}},"alternative-id":["10.1073\/pnas.89.24.12185"],"URL":"https:\/\/doi.org\/10.1073\/pnas.89.24.12185","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1992,12,15]]},"assertion":[{"value":"1992-12-15","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}