Cell surface localization of the 78 kD glucose regulated protein (GRP 78) induced by thapsigargin.
In the present study it was found that the synthesis of the 78 kD glucose-regulated protein (GRP 78 or BIP) is vigorously induced in human rabdomiosarcoma cells (TE 671/RD) following both short-term (1 h) and prolonged (18 h) exposure to 100 nM thapsigargin (Tg). Flow cytometric analysis with a specific anti-GRP 78 polyclonal antibody showed that Tg-treated cells express the GRP 78 on the plasma membrane. Cell surface localization of the Tg-induced GRP 78 was confirmed by biotinylation of membrane-exposed proteins and subsequent isolation of the biotin-labelled proteins by streptavidin/agarose affinity chromatography. It was found that a fraction of the Tg-induced GRP 78 is present among the biotin-labelled, surface-exposed, proteins. Conversely, the GRP 78 immunoprecipitated from unfractionated lysates of Tg-treated and biotin-reacted cells was found to be biotinylated. This is the first report demonstrating surface expression of GRP 78 in cells exposed to a specific GRP 78-inducing stimulus.
Delpino
A
A
Laboratory of Biophysics, Regina Elena Institute for Cancer Research, Rome, Italy.
Piselli
P
P
Vismara
D
D
Vendetti
S
S
Colizzi
V
V
D001710:Biotin / Q000378:metabolism; D019921:Biotinylation; D002352:Carrier Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D005434:Flow Cytometry; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D018832:Molecular Chaperones / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D011233:Precipitin Tests; D012208:Rhabdomyosarcoma; D019284:Thapsigargin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D007143:Immunoglobulin Heavy Chains; D008565:Membrane Proteins; D018832:Molecular Chaperones; D019284:Thapsigargin; D001710:Biotin