ERcalcistorin/protein disulfide isomerase (PDI). Sequence determination and expression of a cDNA clone encoding a calcium storage protein with PDI activity from endoplasmic reticulum of the sea urchin egg.
Following the purification of a 58-kDa calsequestrin-like protein from the endoplasmic reticulum (ER) of sea urchin eggs (Oberdorf, J.A., Lebeche, D., Head, J. F., and Kaminer, B. (1988) J. Biol. Chem. 263, 6806-6809) and its characterization as a high capacity, low affinity calcium-binding protein (Lebeche, D., and Kaminer, B. (1992) Biochem. J. 287, 741-747) we isolated and sequenced a cDNA encoding for this protein. The deduced 496 amino acids contain a 17-residue NH2-terminal signal peptide, a KDEL COOH-terminal ER retention signal and two thioredoxin-like active site domains, -CGHC-, identical with those in protein disulfide isomerase (PDI). The sea urchin egg protein shares a 55% sequence identity with mammalian PDI and its PDI activity is 30% of the activity of rabbit liver PDI. The corresponding mRNA was found in oocytes, mature eggs, embryos, and differentiated tissues of the sea urchin in varying amounts. COS-7 cells transfected with the cDNA, expressed a 58-kDa protein immunoreactive to antibodies against the sea urchin egg protein. This molecule appears to have a dual function of calcium storage and PDI activity within the ER. We hence redesignate it ERcalcistorin/PDI (ECaSt/PDI), a protein that is distinct from calsequestrin and calreticulin.
Lucero
H A
HA
Department of Physiology, Boston University School of Medicine, Massachusetts 02118.
Lebeche
D
D
Kaminer
B
B
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004527:Egg Proteins; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D006801:Humans; D007535:Isomerases / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010063:Ovum / Q000201:enzymology; D019704:Protein Disulfide-Isomerases; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D012617:Sea Urchins; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; C089323:ERcalcistorin protein, Strongylocentrotus purpuratus; D004527:Egg Proteins; D012333:RNA, Messenger; D007535:Isomerases; D019704:Protein Disulfide-Isomerases