{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T20:22:34Z","timestamp":1789935754232,"version":"4.0.1"},"reference-count":0,"publisher":"National Academy of Sciences","issue":"4","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[1994,2,15]]},"abstract":"<jats:p>Two nonhomologous polypeptide toxins, tityustoxin\nK alpha (TsTX-K alpha) and tityustoxin K beta (TsTX-K beta), purified from the\nvenom of the Brazilian scorpion Tityus serrulatus, selectively block\nvoltage-gated noninactivating K+ channels in synaptosomes (IC50 values of 8 nM\nand 30 nM, respectively). In contrast, alpha-dendrotoxin (alpha-DTX) and\ncharybdotoxin (ChTX) block voltage-gated inactivating K+ channels in\nsynaptosomes (IC50 values of 90 nM and 40 nM, respectively). We studied\ninteractions among these toxins in 125I-alpha-DTX binding and 86Rb efflux\nexperiments. Both TsTX-K alpha and ChTX completely displaced specifically bound\n125I-alpha-DTX from synaptic membranes, but TsTX-K beta had no effect on bound\nalpha-DTX. TsTX-K alpha and TsTX-K beta blocked the same noninactivating\ncomponent of 100 mM K(+)-stimulated 86Rb efflux in synaptosomes. Both alpha-DTX\nand ChTX blocked the same inactivating component of the K(+)-stimulated 86Rb\nefflux in synaptosomes. Both the inactivating and the noninactivating components\nof the 100 mM K(+)-stimulated 86Rb efflux were completely blocked when 200 nM\nTsTX-K beta and either 600 nM alpha-DTX or 200 nM ChTX were present. The effects\nof TsTX-K alpha and ChTX on 86Rb efflux were also additive. When TsTX-K alpha\nwas added in the presence of alpha-DTX, however, only the noninactivating\ncomponent of the K(+)-stimulated efflux was blocked. The inactivating component\ncould then be blocked by ChTX, which is structurally homologous to TsTX-K alpha.\nWe conclude that TsTX-K alpha unblocks the voltage-gated inactivating K+\nchannels in synaptosomes when they are blocked by alpha-DTX, but not when they\nare blocked by ChTX. TsTX-K alpha binds to a site on the inactivating K+ channel\nthat does not occlude the pore; its binding apparently prevents alpha-DTX (7054\nDa), but not ChTX (4300 Da), from blocking the pore. The effects of TsTX-K alpha\non 125I-alpha-DTX binding and 86Rb efflux are mimicked by noxiustoxin, which is\nhomologous to TsTX-K alpha and ChTX.<\/jats:p>","DOI":"10.1073\/pnas.91.4.1475","type":"journal-article","created":{"date-parts":[[2006,5,31]],"date-time":"2006-05-31T09:03:29Z","timestamp":1149066209000},"page":"1475-1479","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":85,"title":["Tityustoxin K alpha blocks voltage-gatednoninactivating K+ channels and unblocks inactivating K+ channels blocked byalpha-dendrotoxin in synaptosomes."],"prefix":"10.1073","volume":"91","author":[{"given":"R S","family":"Rogowski","sequence":"first","affiliation":[{"name":"Department of Physiology, University of Maryland School\rof Medicine, Baltimore."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B K","family":"Krueger","sequence":"additional","affiliation":[{"name":"Department of Physiology, University of Maryland School\rof Medicine, Baltimore."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J H","family":"Collins","sequence":"additional","affiliation":[{"name":"Department of Physiology, University of Maryland School\rof Medicine, Baltimore."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"M P","family":"Blaustein","sequence":"additional","affiliation":[{"name":"Department of Physiology, University of Maryland School\rof Medicine, Baltimore."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[1994,2,15]]},"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.91.4.1475","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,4,13]],"date-time":"2022-04-13T13:48:58Z","timestamp":1649857738000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.91.4.1475"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1994,2,15]]},"references-count":0,"journal-issue":{"issue":"4","published-print":{"date-parts":[[1994,2,15]]}},"alternative-id":["10.1073\/pnas.91.4.1475"],"URL":"https:\/\/doi.org\/10.1073\/pnas.91.4.1475","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[1994,2,15]]},"assertion":[{"value":"1994-02-15","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}