title: BiP-dependent export of cholera toxin from endoplasmic reticulum-derived microsomes.
abstract: Cholera toxin (CT) is transported from the cell surface to the endoplasmic reticulum (ER) from where it is translocated to the cytosol in a process depending on ATP and luminal ER proteins. To test whether the molecular chaperone BiP (heavy chain binding protein), which is an ER-luminal ATPase, was one of the required proteins the export of CT was analyzed using ER-derived CT-loaded microsomes. The resubstitution of extracted export-incompetent microsomes with purified BiP was sufficient to restore the export of CT. As BiP protected CT from aggregation it is proposed that BiP maintains CT in a soluble, export-competent state.
authors: Institut für Zellbiologie, Rheinische Friedrich-Wilhelms Universität Bonn, Ulrich-Haberland-Str. 61a, 53121 Bonn, Germany.
authors: Alexandra
authors: A
authors: Winkeler
authors: Daniela
authors: D
authors: Gödderz
authors: Volker
authors: V
authors: Herzog
authors: Anton
authors: A
authors: Schmitz
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport; D016466:CHO Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D002772:Cholera Toxin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D015151:Immunoblotting; D008861:Microsomes / Q000378:metabolism* / Q000648:ultrastructure; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D017510:Protein Folding; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D002772:Cholera Toxin; D000251:Adenosine Triphosphatases