Coordinated nonvectorial folding in a newly synthesized multidomain protein.
The low-density lipoprotein receptor (LDL-R) is a typical example of a multidomain protein, for which in vivo folding is assumed to occur vectorially from the amino terminus to the carboxyl terminus. Using a pulse-chase approach in intact cells, we found instead that newly synthesized LDL-R molecules folded by way of "collapsed" intermediates that contained non-native disulfide bonds between distant cysteines. The most amino-terminal domain acquired its native conformation late in folding instead of during synthesis. Thus, productive LDL-R folding in a cell is not vectorial but is mostly posttranslational, and involves transient long-range non-native disulfide bonds that are isomerized into native short-range cysteine pairs.
Jansens
Annemieke
A
Department of Bio-Organic Chemistry 1, Bijvoet Center for Biomolecular Research, University of Utrecht, Padualaan 8, 3584 CH Utrecht, Netherlands.
van Duijn
Esther
E
Braakman
Ineke
I
D003545:Cysteine / Q000737:chemistry; D004229:Dithiothreitol; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000939:Epitopes; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008024:Ligands; D008970:Molecular Weight; D010084:Oxidation-Reduction; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011973:Receptors, LDL / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D000939:Epitopes; D008024:Ligands; D011973:Receptors, LDL; D003545:Cysteine; D004229:Dithiothreitol