Erp61 is GRP58, a stress-inducible luminal endoplasmic reticulum protein, but is devoid of phosphatidylinositide-specific phospholipase C activity.
Using antibody raised against putative Form I phosphatidylinositide-specific phospholipase C (PI-PLC) and direct amino acid sequencing of the protein recognized by this antibody, we have shown that the antibody reacts with luminal endoplasmic reticulum (ER) proteins, including ERp61. ERp61 possesses a COOH-terminal QEDL sequence that acts as an ER retention signal. Additional experiments have shown, however, that PI-PLC activity is separable from ERp61 and that rat or murine ERp61 expressed in COS cells failed to produce an increase in PI-PLC activity in the COS cells. Finally, we have identified ERp61 as GRP58, a 58-kDa protein inducible by glycosylation block and treatment with the Ca2+ ionophore, A23187.
Mazzarella
R A
RA
Department of Microbiology, Saint Louis University School of Medicine, Missouri 63104.
Marcus
N
N
Haugejorden
S M
SM
Balcarek
J M
JM
Baldassare
J J
JJ
Roy
B
B
Li
L J
LJ
Lee
A S
AS
Green
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D007535:Isomerases; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D010954:Plasmacytoma; D019704:Protein Disulfide-Isomerases; D011994:Recombinant Proteins / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014407:Tumor Cells, Cultured
D018076:DNA, Complementary; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; D008715:Methionine; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D007535:Isomerases; C513196:PDIA3 protein, rat; D019704:Protein Disulfide-Isomerases