{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,7]],"date-time":"2026-02-07T17:54:29Z","timestamp":1770486869302,"version":"3.49.0"},"reference-count":0,"publisher":"Portland Press Ltd.","issue":"3","content-domain":{"domain":["portlandpress.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1997,12,15]]},"abstract":"<jats:p>The Bcl-2 oncoprotein is a key regulator of apoptosis and the Bag-1 protein interacts with Bcl-2 and cooperates with Bcl-2 to suppress apoptosis. The human Bag-1 cDNA is essentially identical with a previously described cDNA encoding RAP46, which interacts with activated steroid hormone receptors. However, there is considerable confusion over the structure of Bag-1\/RAP46 proteins and their relationship to endogenous Bag-1 proteins. Here we have characterized Bag-1 expression in mammalian cells. We demonstrate that, in addition to the previously identified 32 kDa murine and 36 kDa human Bag-1 proteins, cells express a second 50 kDa Bag-1 isoform. In some murine cell lines p50 is expressed at the same level as p32 Bag-1, and p50 and p32 Bag-1 proteins have distinct subcellular localizations, suggesting that they are functionally distinct. The published mouse Bag-1 cDNA is partial, and sequencing of additional murine Bag-1 RNA 5\u02b9 sequences demonstrated that human and murine Bag-1 cDNAs contain longer open reading frames than originally suspected. We determined which open reading frames gave rise to the Bag-1 isoforms in human cells. Suprisingly, translation of neither protein initiated at the first in-frame methionine, and cells do not express Bag-1\/RAP46 proteins with the previously proposed structures; p50 Bag-1 initiates at an upstream CUG codon, whereas p36 Bag-1 initiates at a downstream AUG codon. Therefore, cells express two differently localized Bag-1 isoforms generated by alternative translation initiation, and Bag-1 proteins may play a dual role in regulating apoptosis and steroid hormone-dependent transcription.<\/jats:p>","DOI":"10.1042\/bj3280807","type":"journal-article","created":{"date-parts":[[2015,8,10]],"date-time":"2015-08-10T21:57:14Z","timestamp":1439243834000},"page":"807-813","update-policy":"https:\/\/doi.org\/10.1042\/crossmark_policy","source":"Crossref","is-referenced-by-count":149,"title":["Mammalian cells express two differently localized Bag-1 isoforms generated by alternative translation initiation"],"prefix":"10.1042","volume":"328","author":[{"given":"Graham","family":"PACKHAM","sequence":"first","affiliation":[{"name":"Ludwig Institute for Cancer Research, Imperial College School of Medicine at St Mary's, London W2 1PG, U.K."},{"name":"Virology and Cell Biology, Department of Medical Microbiology, Imperial College School of Medicine at St Mary's, London W2 1PG, U.K."}]},{"given":"Matthew","family":"BRIMMELL","sequence":"additional","affiliation":[{"name":"Ludwig Institute for Cancer Research, Imperial College School of Medicine at St Mary's, London W2 1PG, U.K."}]},{"given":"L. John","family":"CLEVELAND","sequence":"additional","affiliation":[{"name":"Department of Biochemistry, St Jude Children's Research Hospital, Memphis, TN 38105, U.S.A."},{"name":"Department of Biochemistry, University of Tennessee, Memphis, TN 38163, U.S.A."}]}],"member":"288","container-title":["Biochemical Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/328\/3\/807\/630441\/bj3280807.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/portlandpress.com\/biochemj\/article-pdf\/328\/3\/807\/630441\/bj3280807.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,11,24]],"date-time":"2021-11-24T00:55:47Z","timestamp":1637715347000},"score":1,"resource":{"primary":{"URL":"https:\/\/portlandpress.com\/biochemj\/article\/328\/3\/807\/36750\/Mammalian-cells-express-two-differently-localized"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1997,12,15]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1997,12,15]]}},"URL":"https:\/\/doi.org\/10.1042\/bj3280807","relation":{},"ISSN":["0264-6021","1470-8728"],"issn-type":[{"value":"0264-6021","type":"print"},{"value":"1470-8728","type":"electronic"}],"subject":[],"published":{"date-parts":[[1997,12,15]]}}}