we also observed that throughout the period of the chase , the radiolabeled arachidonate remained esterified to the same phospholipid class into which it was initially incorporated ( approximately 40 % of [ 14c ] arachidonate in diacyl phosphatidylcholine , 40 % in phosphatidylinositol , and 15 % in diacyl phosphatidylethanolamine . in cell fractionation experiments , we found that after 1-3 h of chase , [ 14c ] arachidonate decreased in subcellular fractions containing nuclei , as it became progressively unavailable for release from phospholipids . thus , our results indicate that 1 ) upon cell stimulation , the most recently incorporated pool of arachidonate , which is in high concentration in the nuclear membrane , is preferentially released and that 2 ) arachidonate rapidly moves out of the nuclear membrane into a less releasable pool while remaining esterified to the phospholipid moiety into which it was initially incorporated .
C0007610
nuclei
C0007634
cell