ISSN:
1471-4159
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Medizin
Notizen:
Abstract— The de novo synthesis of phosphatidylcholine and phosphatidylethanolamine in isolated neuronal and glial cells from adult rabbit brain cortex was investigated in vitro, using labelled phosphorylcholine (phosphorylethanolamine) or cytidine-5′-phosphate choline (cytidine-5′-phosphate ethanolamine), as lipid precursors. Synthesis of phospholipid from phosphorylcholine and phosphorylethanolamine in both fractions was extremely low when compared to that derived from the corresponding cytidine nucleotides. The neuronal cell-enriched fraction was found to possess a much higher rate of synthesis of both lipids from all precursors. Neuronal/glial ratios of about 5–9 were found for the synthesis of phosphatidylcholine and phosphatidylethanolamine from cytidine-5′-phosphate choline and cytidine-5′-phosphate ethanolamine, respectively. Several kinetic properties of the choline-phosphotransferase (EC 2.7.8.2) and ethanolaminephosphotransferase (EC 2.7.8.1) were found to be similar both in neurons and in glia (e.g. Km of cytidine-5′-phosphate ethanolamine, Km of diacyl glycerol, pH optimum, need for divalent cations), but the Km value for cytidine-5′-phosphate choline in glial cells was much lower (2.3 × 10−4m) than in neurons (1 × 10−3m). The Kmfor cytidine-5′-phosphate ethanolamine in both cells was much lower than in whole brain microsomes. It is concluded that the cytidine-dependent enzymic system for phosphatidylcholine and phosphatidylethanolamine synthesis is concentrated mostly in the neuronal cells, as compared to glia.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1111/j.1471-4159.1973.tb07561.x
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