Folding and maturation of tyrosinase-related protein-1 are regulated by the post-translational formation of disulfide bonds and by N-glycan processing.
In this study we have explored the endoplasmic reticulum associated events accompanying the maturation of the tyrosinase-related protein-1 (TRP-1) nascent chain synthesized in mouse melanoma cells. We show that TRP-1 folding process occurs much more rapidly than for tyrosinase, a highly homologous protein, being completed post-translationally by the formation of critical disulfide bonds. In cells pretreated with dithiothreitol (DTT), unfolded TRP-1 is retained in the endoplasmic reticulum by a prolonged interaction with calnexin and BiP before being targeted for degradation. The TRP-1 chain was able to fold into DTT-resistant conformations both in the presence or absence of alpha-glucosidase inhibitors, but folding occurred through different pathways. During the normal folding pathway, TRP-1 interacts with calnexin. In the presence of alpha-glucosidase inhibitors, the interaction with calnexin is prevented, with TRP-1 folding being assisted by BiP. In this case, the process has similar kinetics to that of untreated TRP-1 and yields a compact form insensitive to DTT as well. However, this form has different thermal denaturation properties than the native conformation. We conclude that disulfide bridge burring is crucial for the TRP-1 export. This suggests that although various folding pathways may complete this process, the native form may be acquired only through the normal unperturbed pathway.
Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, 77700 Bucharest, Romania.
G
G
Negroiu
R A
RA
Dwek
S M
SM
Petrescu
D017485:1-Deoxynojirimycin / Q000031:analogs & derivatives / Q000494:pharmacology; D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism; D037281:Calnexin; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000201:enzymology / Q000378:metabolism; D065089:Glycoside Hydrolase Inhibitors; D006596:Hexosaminidases / Q000378:metabolism; D007700:Kinetics; D008545:Melanoma / Q000378:metabolism / Q000473:pathology; D008562:Membrane Glycoproteins; D051379:Mice; D018832:Molecular Chaperones / Q000378:metabolism; D010088:Oxidoreductases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011134:Polysaccharides / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation / Q000187:drug effects; D011489:Protein Denaturation / Q000187:drug effects; D017510:Protein Folding; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D013816:Thermodynamics; D014407:Tumor Cells, Cultured; D000520:alpha-Glucosidases / Q000378:metabolism
D002135:Calcium-Binding Proteins; D004220:Disulfides; D065089:Glycoside Hydrolase Inhibitors; D008562:Membrane Glycoproteins; D018832:Molecular Chaperones; D011134:Polysaccharides; D011506:Proteins; D037281:Calnexin; D017485:1-Deoxynojirimycin; C059896:miglustat; D010088:Oxidoreductases; C079621:Tyrp1 protein, mouse; C064056:tyrosinase-related protein-1; D006596:Hexosaminidases; D000520:alpha-Glucosidases; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D004229:Dithiothreitol