Phosphatidylserine synthesis in glioma C6 cells is inhibited by Ca2+ depletion from the endoplasmic reticulum: effects of 2,5-di-tert-butylhydroquinone and thimerosal.
The effects of 2,5-di-tert-butylhydroquinone (DBHQ) and thimerosal on phosphatidylserine synthesis by the base exchange reaction and on calcium mobilization in intact glioma C6 cells were compared with that of thapsigargin, a selective inhibitor of the endoplasmic reticulum Ca(2+)-ATPase. It has been found that all these agents inhibit phosphatidylserine synthesis by 70%, but their effectiveness are different. The data show that this inhibition is caused by Ca2+ depletion of the endoplasmic reticulum, indicating that phosphatidylserine synthesis requires high concentration of Ca2+ within this structure. On this basis and on literature data, a new model for the localization of the serine base exchange enzyme in the endoplasmic reticulum membrane is proposed.
Wiktorek
M
M
Department of Cellular Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland.
Sabała
P
P
Czarny
M
M
Barańska
J
J
D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005910:Glioma / Q000378:metabolism* / Q000473:pathology; D006873:Hydroquinones / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D010718:Phosphatidylserines / Q000096:biosynthesis*; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin; D013849:Thimerosal / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D006873:Hydroquinones; D010718:Phosphatidylserines; D013729:Terpenes; D013849:Thimerosal; C019359:2,5-di-tert-butylhydroquinone; D015759:Ionomycin; D019284:Thapsigargin; D000252:Calcium-Transporting ATPases; D002118:Calcium