The ability of muscarinic cholinergic agonists to interact with muscarinic receptors in nerve ending preparations and elicit an increased labeling of phosphatidate and phosphatidylinositol from 32Pi has been investigated. Two groups of brain muscarinic agonists are distinguished. Addition of acetylcholine, carbamylcholine, methacholine, or muscarine resulted in a 2-fold stimulation of phosphati...

the effects of therapeutic doses of dillsun, garsin, antum and statins on rat liver cytosolic phosphatidate phosphohydrolase (pap) activity, a key enzyme in triacylglycerol synthesis, and on serum and liver lipids were examined. lovastatin and simvastatin both stimulated the enzyme activity by 29% and 43%, respectively. the stimulatory effects were dose-dependent and accompanied by the decline ...

The mechanism by which bi-and trivalent cations affect human liver phosphatidatephosphohydrolase (PAP) activity was investigated. Bivalent cations up to 1 mM increased PAP activity whereas at higher concentrations the activity of the enzyme decreased. The stimulatory concentration for trivalent cations such as Al3+ and Cr3+, however, was much lower being 2 m M and 1 m M, respectively. All catio...

Interest in our laboratory in the inositol lipids derives from the presence of relatively high amounts of phosphatidylinositol phosphate (PhIP) and phosphatidylinositol diphosphate (PhIPP) in excitable tissue. It was with this relationship in mind that we embarked on a study of biosynthetic pathways of inositol lipids several years ago. A first step in the elucidation of biosynthetic pathways o...

We found that glucagon stimulated membrane protein kinase C (PKC) activity and phosphatidylcholine hydrolysis in 24 h-cultured rat hepatocytes. Phorbol myristate acetate, 8-bromo cyclic AMP, vasopressin, noradrenaline and the Ca2+ ionophore A23187 also stimulated membrane PKC activity. However, only vasopressin and noradrenaline stimulated inositol phosphate accumulation, whereas all agonists s...

A sensitive radioactive assay of acyl CoA:sn-glycerol-3-phosphate-O-acyltransferase (EC 2.3.1.15) was developed to study the properties and subcellular distribution of this enzyme in rat epididymal adipose tissue. The esterification of sn-glycerol-3-phosphate was measured in the presence of palmitoyl CoA or palmitate, ATP, CoA, and Mg(2+) at pH 7.5. The presence of glycerophosphate acyltransfer...

The Saccharomyces cerevisiae DPP1-encoded diacylglycerol pyrophosphate phosphatase catalyzes the dephosphorylation of diacylglycerol pyrophosphate to form phosphatidate and Pi. The enzyme also dephosphorylates phosphatidate to form diacylglycerol and Pi. Because diacylglycerol pyrophosphate, phosphatidate, and diacylglycerol have roles as lipid signal molecules in higher eukaryotic cells, it is...

The regulation of purified yeast membrane-associated phosphatidylserine synthase (CDP-diacylglycerol:L-serine O-phosphatidyltransferase, EC 2.7.8.8) and phosphatidylinositol synthase (CDP-diacylglycerol:myo-inositol 3-phosphatidyltransferase, EC 2.7.8.11) activities by phospholipids was examined using Triton X-100/phospholipid mixed micelles. Phosphatidate, phosphatidylcholine, and phosphatidyl...

The initiation of receptor-mediated small artery contraction is dependent on inositol 1,4,5-trisphosphatestimulated release of stored calcium. The role of the other product of inositol lipid hydrolysis, 1,2-diacylglycerol, in maintaining contraction remains controversial. Therefore, we have determined the contractile response of rat subcutaneous small arteries (<300 ,m i.d.), when mounted as ri...

Lipid phosphate phosphohydrolase (LPP)-1 cDNA was cloned from a rat liver cDNA library. It codes for a 32-kDa protein that shares 87 and 82% amino acid sequence identities with putative products of murine and human LPP-1 cDNAs, respectively. Membrane fractions of rat2 fibroblasts that stably expressed mouse or rat LPP-1 exhibited 3.1-3. 6-fold higher specific activities for phosphatidate dephos...