Accumulation and degradation in the endoplasmic reticulum of a truncated ER-60 devoid of C-terminal amino acid residues.
The accumulation and degradation in the endoplasmic reticulum (ER) of a truncated ER-60 protease, from which the C-terminal 89 amino acid residues have been deleted (K 417 ochre), was examined. K 417 ochre overexpressed in COS-1 cells is not secreted into the medium, but accumulates as insoluble aggregates in non-ionic detergent without degradation in unusual clump membrane structures. K 417 ochre, stably expressed, forms soluble aggregates in non-ionic detergent and is distributed in the reticular structures of ER. Under these conditions, K 417 ochre is not secreted into the medium but is degraded with a half-life time of more than 8 h. Since K 417 ochre/C all S, in which all the Cys residues of K 417 ochre are replaced by Ser, also forms aggregates, an inter-disulfide bond appears unnecessary for aggregation. In both types of aggregates, Ig heavy chain binding protein, calnexin, glucose regulated protein 94, calreticulin, ERp72, and protein disulfide isomerase are scarcely found. Since degradation of the stably expressed K 417 ochre was not inhibited by lactacystin, leupeptin, NH(4)Cl, or cytocharasin B, but was inhibited by N-acetyl-leucyl-leucyl-norleucinal, the self-aggregated abnormal protein in the lumen of ER is assumed to be degraded by an unknown protease system other than proteasome, lysosome or autophagy.
Urade
R
R
Research Institute for Food Science, Kyoto University, Uji, Kyoto 611-0011, Japan. urade@soya.food.kyoto-u.ac.jp
Kusunose
M
M
Moriyama
T
T
Higasa
T
T
Kito
M
M
D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D019556:COS Cells / Q000187:drug effects / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism; D037281:Calnexin; D037282:Calreticulin; D002352:Carrier Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D003470:Culture Media; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006207:Half-Life; D006360:Heat-Shock Proteins; D007976:Leupeptins / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism
D002135:Calcium-Binding Proteins; D037282:Calreticulin; D002352:Carrier Proteins; D003470:Culture Media; D015853:Cysteine Proteinase Inhibitors; D000091342:Endoplasmic Reticulum Chaperone BiP; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D007976:Leupeptins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; C018551:glucose-regulated proteins; C063261:acetylleucyl-leucyl-norleucinal; C067713:lactacystin; D037281:Calnexin; D003571:Cytochalasin B; D003546:Cysteine Endopeptidases; C077733:ER-60 protease; D019704:Protein Disulfide-Isomerases; C032854:leupeptin; D000111:Acetylcysteine