Freezing of plant tissue adversely affects lipid composition. Immature soybean cotyledons (Glycine max L. Merr.) var. "Harosoy 63" were frozen with liquid N(2), dry ice, or stored in a freezer (-20 C) before lipid extraction. The effects of freezing temperature, thawing rate, and cold storage on the lipid composition of frozen tissue revealed significantly higher levels of phosphatidic acid, an...

Evidence for the involvement of Ca(2+) and calmodulin in the regulation of phospholipid breakdown by microsomal membranes from bean cotyledons has been obtained by following the formation of radiolabeled degradation products from [U-(14)C]phosphatidylcholine. Three membrane-associated enzymes were found to mediate the breakdown of [U-(14)C] phosphatidylcholine, viz. phospholipase D (EC 3.1.4.4)...

CTP-phosphatidic acid cytidylyltransferase (CDP-diglyceride synthetase) is a key enzyme in the biogenesis of membrane phospholipids in Escherichia coli. Using a modification of a previously described autoradiographic screening procedure (Raetz, C. R. H. (1975) h c . Natl. A d Sei. U. S. A. 72, 2274-2278), we have isolated six mutant strains in which the specific activity of the synthetase...

We tested the hypothesis that membrane lipid composition influences drug action at membrane proteins by studying local anesthetic action at the nicotinic acetylcholine receptor (nAChR). Infrared difference spectra show that concentrations of tetracaine consistent with binding to the ion channel (<50 microM) stabilize a resting-like state when the nAChR is reconstituted into phosphatidylcholine ...

We previously purified a cytosolic phospholipase A1 that could catalyze the preferential hydrolysis of phosphatidic acid in mixed-micelle assays. Here we studied the enzyme's interactions with unilamellar lipid membranes and examined effects of the lipids on enzyme binding, stability, and catalysis. A major finding was that membrane lipids could influence the stability, activity, and specificit...

Thrombin-induced aggregation and serotonin release were markedly enhanced in platelets from spontaneously hypertensive rats (SHR) when compared with those from normotensive Wistar-Kyoto rats (WKY). Since phosphoinositides are involved in calcium-mediated platelet responses, the metabolism of these lipids was investigated in SHR and WKY by using 32P-labeled quiescent platelets. In unstimulated c...

CTP-phosphatidic acid cytidylyltransferase (CDP-diglyceride synthetase) is a key enzyme in the biogenesis of membrane phospholipids in Escherichia coli. Using a modification of a previously described autoradiographic screening procedure (Raetz, C. R. H. (1975) Proc. Natl. Acad. Sci. U.S.A. 72, 2274-2278), we have isolated six mutant strains in which the specific activity of the synthetase is 1 ...

In this paper we report on the uptake and distribution of an exogenously supplied fluorescent phosphatidic acid analogue by Chinese hamster fibroblasts. Under appropriate in vitro incubation conditions, 1-acyl-2-(N-4-nitrobenzo-2-oxa-1,3-diazole)-aminocaproyl phosphatidic acid was rapidly and preferentially transferred from phospholipid vesicles to cells at 2 degrees C. However, unlike similar ...

The purpose of this study was to quantify the degree of suppression of the perceived bitterness of quinine by various substances and to examine the mechanism of bitterness suppression. The following compounds were tested for their ability to suppress bitterness: sucrose, a natural sweetener; aspartame, a noncaloric sweetener; sodium chloride (NaCl) as the electrolyte; phosphatidic acid, a comme...

Background: Pah1p is a phosphatidic acid phosphatase that generates diacylglycerol. Results: Deletion of PAH1 alters the sorting of fusion factors to the vacuole and inhibits fusion. Conclusion: Conversion of phosphatidic acid to diacylglycerol is integral to vacuole homeostasis. Significance: This is the first report that links a Lipin1 homologue to the recruitment and activation of a Rab GTPa...