title: Release of the glucose-regulated protein 94 by baby hamster kidney cells.
abstract: Glucose-regulated protein 94 (grp94) is a major component of the endoplasmic reticulum (ER) lumen of eukaryotic cells. We showed that grp94 is released from baby hamster kidney (BHK-21) cells into a serum-free medium. The exit of grp94 into the medium was not related to the protein discharge due to cell death and was independent of de novo protein synthesis. The treatment of cells with brefeldin A and monensin, the inhibitors of the classical pathway of protein secretion, did not decrease the extracellular level of grp94, indicating that the discharge of grp94 from cells does not occur through the ER/Golgi-dependent pathway. Exosomes, membrane vesicles secreted by several cell types, were not involved in the release of grp94 from cells. Methyl-β-cyclodextrin, a substance that disrupts the lipid raft organization, considerably reduced the extracellular level of grp94, indicating that lipid rafts are involved in the liberation of grp94 from BHK-21 cells. The results suggest that BHK-21 cells release grp94 into the serum-free medium via the nonclassical secretory pathway in which lipid rafts play an important role.
authors.affiliation: Laboratory of Cell Cultures and Cellular Engineering, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, 142290, Russia.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Evdokimovskaya
authors.forename: Yuri
authors.initials: Y
authors.lastname: Skarga
authors.forename: Veronika
authors.initials: V
authors.lastname: Vrublevskaya
authors.forename: Oleg
authors.initials: O
authors.lastname: Morenkov
mesh_terms: D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002460:Cell Line; D006224:Cricetinae; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D055354:Exosomes / Q000378:metabolism; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D021962:Membrane Microdomains / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D008985:Monensin / Q000494:pharmacology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D011500:Protein Synthesis Inhibitors; D047392:beta-Cyclodextrins; C018551:glucose-regulated proteins; C108732:methyl-beta-cyclodextrin; D020126:Brefeldin A; D008985:Monensin