title: KDEL proteins are found on the surface of NG108-15 cells.
abstract: Although KDEL proteins are primarily localized to the endoplasmic reticulum (ER), we have employed surface biotinylation method to demonstrate that the KDEL proteins calreticulin (Crt), protein disulfide isomerase (PDI) and the 78-kDa glucose regulated protein (GRP78) are found on the surface of the NG108-15 cell line. In contrast, the 94-kDa glucose regulated protein (GRP94), another KDEL protein, is not found on the cell surface. Calnexin (Cnx), a type-1 integral transmembrane ER protein which is partially homologous to Crt but lacks the KDEL sequence, is not detected on the cell surface either. While only small amounts of the total GRP78, PDI and Crt molecules exist on the cell surface at steady state, a significant fraction of the newly synthesized molecules are transported to the cell surface and transport of these proteins is inhibited by treatment with brefeldin A. The surface GRP78 contains the KDEL sequence. On the cell surface, GRP78, PDI and Crt associate with other proteins and form complexes of different sizes. Surface Crt is found to be essential for the neurite formation when NG108-15 cells are induced to differentiate using dibutyryl cAMP.
authors.affiliation: Department of Chemistry, Boston University, Boston, MA 02215, USA.
authors.forename: G
authors.initials: G
authors.lastname: Xiao
authors.forename: T F
authors.initials: TF
authors.lastname: Chung
authors.forename: H Y
authors.initials: HY
authors.lastname: Pyun
authors.forename: R E
authors.initials: RE
authors.lastname: Fine
authors.forename: R J
authors.initials: RJ
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D019921:Biotinylation; D020126:Brefeldin A / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology; D037282:Calreticulin; D002352:Carrier Proteins / Q000032:analysis* / Q000737:chemistry; D004721:Endoplasmic Reticulum / Q000737:chemistry; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D008565:Membrane Proteins / Q000737:chemistry*; D051379:Mice; D018832:Molecular Chaperones / Q000032:analysis* / Q000737:chemistry; D009363:Neoplasm Proteins / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D016501:Neurites / Q000737:chemistry / Q000187:drug effects; D009447:Neuroblastoma / Q000737:chemistry* / Q000473:pathology; D009474:Neurons / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D019704:Protein Disulfide-Isomerases / Q000032:analysis* / Q000737:chemistry; D017434:Protein Structure, Tertiary; D018000:Receptors, Peptide / Q000378:metabolism; D012261:Ribonucleoproteins / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000276:immunology; D014407:Tumor Cells, Cultured / Q000737:chemistry
chemical_list: D000911:Antibodies, Monoclonal; D002135:Calcium-Binding Proteins; D037282:Calreticulin; D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; C000717248:Hspa5 protein, mouse; C064459:KDEL receptor; D008565:Membrane Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D018000:Receptors, Peptide; D012261:Ribonucleoproteins; D020126:Brefeldin A; D003994:Bucladesine; D019704:Protein Disulfide-Isomerases