caa a22 4500 465766617 CHVBK 20180323111915.0 cr unu---uuuuu 170327e19900501xx s 000 0 eng 10.1007/BF02544387 doi (NATIONALLICENCE)springer-10.1007/BF02544387 Metabolism of phosphatidylinositol in plasma membranes and synaptosomes of rat cerebral cortex: A comparison between endogenous Vs exogenous substrate pools [Elektronische Daten] [Meena Navidi, Ronald MacQuarrie, Grace Sun] The metabolism of phosphatidylinositols (PI) labeled with [14C]arachidonic acid within plasma membranes or synaptosomes was compared to the metabolism of PI prelabeled with [14C]arachidonic acid and added exogenously to the same membranes. Incubation of membranes containing the endogenously-labeled PI pool in the presence of Ca2+ resulted in the release of labeled arachidonic acid, as well as a small amount of labeled diacylglycerol. Labeled arachidonic acid was effectively reutilized and returned to the membrane phospholipids in the presence of adenosine triphosphate (ATP), CoA, and lysoPI. Although Ca2+ promoted the release of labeled diacylglycerol from prelabeled plasma membranes, this amount was only 17% of the maximal release, i.e., release in the presence of deoxycholate and Ca2+. This latter condition is known to fully activate the PI-phospholipase C, and incubation of prelabeled plasma membranes resulted in a six-fold increase in labeled diacylglycerols. On the other hand, when exogenously labeled PI were incubated with plasma membranes in the presence of Ca2+, the labeled diacylglycerols released were 59% of that compared to the fully activated condition. The phospholipase C action was calcium-dependent, regardless of whether exogenous or endogenous substrates were used in the incubation. In contrast to plasma membranes, intact synaptosomes had limited ability to metabolize exogenous PI even in the presence of Ca2+, although the activity of phospholipase C was similar to that in the plasma membranes when assayed in the presence of deoxycholate and Ca2+. These results suggest that discrete pools of PI are present in plasma membranes, and that the pool associated with the acyltransferase is apparently not readily accessible to hydrolysis by phospholipase C. American Oil Chemists' Society, 1990 Navidi Meena Sinclair Comparative Medicine Research Farm and Department of Biochemistry, University of Missouri, 65203, Columbia, MO aut MacQuarrie Ronald School of Basic Life Sciences, University of Missouri-Kansas City, 64110, Kansas City, MO aut Sun Grace Sinclair Comparative Medicine Research Farm and Department of Biochemistry, University of Missouri, 65203, Columbia, MO aut Lipids Springer-Verlag 25/5(1990-05-01), 273-277 0024-4201 25:5<273 1990 25 11745 https://doi.org/10.1007/BF02544387 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02544387 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Navidi Meena Sinclair Comparative Medicine Research Farm and Department of Biochemistry, University of Missouri, 65203, Columbia, MO aut NATIONALLICENCE 700 1- MacQuarrie Ronald School of Basic Life Sciences, University of Missouri-Kansas City, 64110, Kansas City, MO aut NATIONALLICENCE 700 1- Sun Grace Sinclair Comparative Medicine Research Farm and Department of Biochemistry, University of Missouri, 65203, Columbia, MO aut NATIONALLICENCE 773 0- Lipids Springer-Verlag 25/5(1990-05-01), 273-277 0024-4201 25:5<273 1990 25 11745 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer