{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,5]],"date-time":"2026-10-05T11:16:39Z","timestamp":1791198999166,"version":"4.1.0"},"reference-count":0,"publisher":"Portland Press Ltd.","issue":"1","content-domain":{"domain":["portlandpress.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1989,8,15]]},"abstract":"<jats:p>Okadaic acid, a tumour promoter which potently inhibits protein phosphatases, inhibited translation in the reticulocyte-lysate cell-free system. Inhibition was dose-dependent, with half-maximal effects occurring at 20-40 nM-okadaic acid. Inhibition of translation by okadaic acid resulted in the accumulation of polyribosomes, indicating that it was due to a decrease in the rate of elongation relative to initiation. Okadaic acid (at concentrations which inhibited translation) caused increased phosphorylation of a number of proteins in the lysate. Prominent among these was a protein of Mr 100,000, which has previously been identified as elongation factor 2 (EF-2). EF-2 is a specific substrate for a Ca2+\/calmodulin-dependent protein kinase, which phosphorylates EF-2 on threonine residues. The Mr-100,000 band was phosphorylated exclusively on threonine residues, and its degree of 32P labelling was decreased by the Ca2+ chelator EGTA and by the calmodulin antagonist trifluoperazine. These agents attenuated the effects of okadaic acid on EF-2 phosphorylation and translation. When ranges of concentrations of each agent were tested, their effects on EF-2 labelling correlated well with their ability to reverse the okadaic acid-induced inhibition of translation. These findings demonstrate that increased phosphorylation of EF-2 results in an impairment of peptide-chain elongation when natural mRNA is used. The possible physiological role of EF-2 phosphorylation in the control of translation is discussed.<\/jats:p>","DOI":"10.1042\/bj2620069","type":"journal-article","created":{"date-parts":[[2015,8,10]],"date-time":"2015-08-10T21:14:08Z","timestamp":1439241248000},"page":"69-75","update-policy":"https:\/\/doi.org\/10.1042\/crossmark_policy","source":"Crossref","is-referenced-by-count":82,"title":["The tumour promoter okadaic acid inhibits reticulocyte-lysate protein synthesis by increasing the net phosphorylation of elongation factor 2"],"prefix":"10.1042","volume":"262","author":[{"given":"N T","family":"Redpath","sequence":"first","affiliation":[{"name":"Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, U.K."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C G","family":"Proud","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, U.K."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"288","container-title":["Biochemical Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/262\/1\/69\/597593\/bj2620069.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/262\/1\/69\/597593\/bj2620069.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,11,25]],"date-time":"2021-11-25T18:32:17Z","timestamp":1637865137000},"score":1,"resource":{"primary":{"URL":"https:\/\/portlandpress.com\/biochemj\/article\/262\/1\/69\/26175\/The-tumour-promoter-okadaic-acid-inhibits"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1989,8,15]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1989,8,15]]}},"URL":"https:\/\/doi.org\/10.1042\/bj2620069","relation":{},"ISSN":["0264-6021","1470-8728"],"issn-type":[{"value":"0264-6021","type":"print"},{"value":"1470-8728","type":"electronic"}],"subject":[],"published":{"date-parts":[[1989,8,15]]}}}