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The Influence of Divalent Cations and Substrate Concentration on the Incorporation of Myo‐inositol into Phospholipids of Isolated Bovine Oligodendrocytes
Author(s) -
Gibson A.,
Brammer M. J.
Publication year - 1981
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1981.tb01674.x
Subject(s) - inositol , divalent , phosphatidylinositol , chemistry , diacylglycerol kinase , biochemistry , substrate (aquarium) , inositol phosphate , diglyceride , enzyme , biology , receptor , protein kinase c , signal transduction , ecology , organic chemistry
The incorporation of myo‐inositol into phosphatidylinositol by two routes (CTP‐dependent and CTP‐independent) has been investigated in homogenates prepared from isolated bovine oligodendrocyte perikarya. The CTP‐dependent route has the higher maximum velocity of inositol incorporation and can utilise either Mn 2+ or Mg 2+ as a divalent ion cofactor. This route of inositol incorporation is also strongly inhibited by Ca 2+ ions at concentrations less than 1 mM. The primary site of the inhibitory action appears to be the enzyme CDP‐diglyceride inositol phosphatidyl transferase (EC 2.7.8.11) though synthesis of CDP‐diacylglycerol is also inhibited by endogenous Ca 2+ present in the oligodendrocyte homogenate. In contrast, CTP‐independent inositol incorporation into phosphatidylinositol is only stimulated by Mn 2+ (Zn 2+ , Cu 2+ , Mg 2+ , Ca 2+ and Co 2+ are ineffective) and is not inhibited by Ca 2+ , at least up to a concentration of 1 mM.