The incorporation of P32 into the inositol phosphatides of rat brain

Abstract

The inositol phosphatide fraction of rat brain has been separated by chromatography on formaldehyde-treated paper into monophosphoinositide and two other inositol-containing phosphatides named phosphoinositide 1 and 2. Quantitative determination of the ether-soluble phosphatides gave the following values for rat brains of 450 to 500 mg dry weight: 14 to 21 mg phosphatidylcholine and phosphatidylethanolamine, 3.5 to 4.6 mg phosphatidylserine, 0.9 to 1.3 mg monophosphoinositide, and 0.1 to 0.2 mg each of phosphoinositide 1 and 2. All three inositol phosphatides incorporated P32 at a significantly higher rate than the other brain phosphatides. Of the three, monophosphoinositide always had the lowest specific activity; after 16 and 32 hours, phosphoinositide 2, which is probably identical with the triphosphoinositide of Ballou, had the highest specific activity.