Recent studies have demonstrated the existence of a novel family of calcium-independent plasmalogen-selective phospholipases A2 in canine myocardium that have been implicated as enzymic mediators of ischemic membrane damage. We now report that human myocardium contains two functionally distinct isoforms of cytosolic calcium-independent phospholipase A2. The major cytosolic phospholipase A2 isof...

Specialized plasma membrane domains known as lipid rafts participate in signal transduction and other cellular processes, and their liquid-ordered properties appear to be important for their function. We investigated the possibility of using amphiphiles to disrupt lipid rafts and thereby inhibit IgE-FcepsilonRI signaling. We find that short-chain ceramides - C2-ceramide and C6-ceramide - decrea...

A granule-associated phospholipase A2 from rabbit polymorphonuclear leukocytes and a closely similar phospholipase A2 from rabbit serum have been purified to near homogeneity by ion-exchange and reverse-phase chromatography. The cellular (polymorphonuclear leukocyte) phospholipase A2 has been purified greater than 100,000-fold and the extracellular (serum) phospholipase A2 approximately 60,000-...

Since the classical, pioneering studies of Beaufay and De Duve [ 11, it has been known that glucose-6phosphohydrolase (G-6-Pase) is a phospholipid-dependent enzyme. However, the specificity of this dependence is still unknown. Duttera et al. [2] found that Cl. welchii phospholipase C, which hydrolyses microsomal phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin, causes 8...

[3H]Myristoyl-labeled variant surface glycoprotein (VSG) has been isolated from Trypanosoma brucei by reverse phase high performance liquid chromatography and used as substrate for the conversion by trypanosomal enzymes of membrane-form VSG to soluble VSG. Conversion is detected by the release of myristoyl-containing lipids. The major lipolytic enzyme of T. brucei, phospholipase A1, is effectiv...

A phospholipase inhibitor (WSG) has been purified from Withania somnifera using gel-filtration and ion-exchange chromatographies. The WSG is an acidic glycoprotein. Its molecular mass as determined by SDS-PAGE was 27kDa. It neutralized the enzyme activity and pharmacological properties such as cytotoxicity, edema, and myotoxicity of a multi-toxic Indian cobra venom phospholipase (NNXIa-PLA) but...

Phospholipase A 1/A2, Macrophages, Arachidonic Acid, Acylchain Specificity The fatty acyl specificity of phospholipase A[ and A2 in homogenates of mouse bone marrowderived macrophages was determined using phosphatidylcholine and phosphatidylethanolamine of different acylchain composition. Phosphatidylcholine with arachidonoyl at position 2 was cleaved preferentially by an alkaline phospholipase...

The 85 kDa cytosolic phospholipase A2 is the key enzyme in the release of arachidonic acid. To gain insight into cytosolic phospholipase A2 action in mitogen-activated cells, the localization of the phospholipase was investigated in fibroblasts upon stimulation with epidermal growth factor and the calcium ionophore A23187. By the use of indirect immunofluorescence microscopy, staining of endoge...

Addition of epidermal growth factor to A431 cells results in dramatic changes in cell morphology. Initially the cells form membrane ruffles accompanied by increased actin polymerization, followed by cell rounding. Activation of the tyrosine kinase of the receptor by binding epidermal growth factor leads also to phosphorylation and activation of phospholipase C-gamma 1, a key enzyme in the phosp...

In Dictyostelium discoideum extracellular cAMP induces chemotaxis via a transmembrane signal transduction cascade consisting of surface cAMP receptors, G-proteins and effector enzymes including adenylyl cyclase, guanylyl cyclase and phospholipase C. Previously it was demonstrated that some cAMP derivatives such as 3'-deoxy-3'-aminoadenosine 3':5'-monophosphate (3'NH-cAMP) bind to the receptor a...