Folding of human intestinal lactase-phlorizin hydrolase.
The folding of human intestinal prolactase-phlorizin hydrolase (pro-LPH) has been analyzed in a cell-free transcription/translation system. In the presence of the thiol oxidant GSSG, disulfide bond formation in pro-LPH can be promoted concomitant with the binding of the molecule to a conformation-specific monoclonal anti-LPH antibody. Under these conditions, pro-LPH does not bind to the molecular chaperone BiP. In the absence of GSSG, on the other hand, pro-LPH does not bind to the monoclonal anti-LPH antibody, but can be immunoprecipitated with a polyclonal antibody that is directed against a denatured form of the enzyme. In this case, interaction of pro-LPH with immunoglobulin heavy chain binding protein can be discerned. The results demonstrate the existence of intramolecular disulfide bonds that are essential for the promotion of pro-LPH to a native conformation. Furthermore, BiP is involved in the folding events of pro-LPH.
Jacob
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Institute of Microbiology, Heinrich Heine University, Düsseldorf, Federal Republic of Germany.
Bulleid
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Naim
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000478:Alkylation; D001706:Biopsy; D002352:Carrier Proteins / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D000091342:Endoplasmic Reticulum Chaperone BiP; D004792:Enzyme Precursors / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005978:Glutathione / Q000031:analogs & derivatives / Q000494:pharmacology; D019803:Glutathione Disulfide; D006360:Heat-Shock Proteins; D006801:Humans; D007421:Intestine, Small / Q000201:enzymology; D007422:Intestines / Q000201:enzymology*; D010694:Lactase-Phlorizin Hydrolase / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008871:Microvilli / Q000201:enzymology; D018832:Molecular Chaperones / Q000378:metabolism; D010084:Oxidation-Reduction; D017510:Protein Folding; D011994:Recombinant Proteins / Q000378:metabolism; D014357:Trypsin / Q000494:pharmacology
D002352:Carrier Proteins; D004220:Disulfides; D000091342:Endoplasmic Reticulum Chaperone BiP; D004792:Enzyme Precursors; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D010694:Lactase-Phlorizin Hydrolase; D014357:Trypsin; D005978:Glutathione; D019803:Glutathione Disulfide