Phospholipase A2 products retain a neuron specific γ isoform of PKC on the plasma membrane through the C1 domain—a molecular mechanism for sustained enzyme activity

2004 ◽  
Vol 45 (1) ◽  
pp. 39-47 ◽  
Author(s):  
K Yagi
Keyword(s):  
Enzyme Activity ◽  
Plasma Membrane ◽  
Phospholipase A2 ◽  
Molecular Mechanism ◽  
C1 Domain

Exterior and Interior Events in Early Stage of Thrombin-induced Platelet Aggregation

1977 ◽  
Vol 38 (03) ◽  
pp. 0630-0639 ◽  
Author(s):  
Shuichi Hashimoto ◽  
Sachiko Shibata ◽  
Bonro Kobayashi
Keyword(s):  
Molecular Weight ◽  
Enzyme Activity ◽  
Plasma Membrane ◽  
Platelet Aggregation ◽  
Early Stage ◽  
Adenyl Cyclase ◽  
Cellular Component ◽  
Primary Event ◽  
Rabbit Platelets ◽  
Membrane Bound

SummaryTreatment of washed rabbit platelets with 1 u/ml of thrombin at 37° C resulted in a disappearance from platelets of a protein with 250,000 dalton molecular weight which was shown to be originated from plasma membrane. Parallel loss of adenyl cyclase was noted, and both reactions were complete within 30 sec. From the patterns of disc electrophoretograms, the importance of quick suppression of thrombin action in demonstrating the primary event was stressed.Thrombin induced an apparent activation of membrane bound phosphodiesterase. This reaction was also complete within 30 sec. The cellular component which contained the enzyme activity was distinct from plasma membrane. Soluble phosphodiesterase was not influenced by thrombin at all.These reactions required intact platelet cells to react with thrombin, and no reaction was detected when subcellular preparations were treated with thrombin.Possibility of collaboration of changes in externally located synthetic enzyme with those in internally located degrading enzyme in the early phase of thrombin action on platelets was suggested.

scholarly journals ULTRASTRUCTURAL LOCALIZATION OF Mg++-DEPENDENT DINITROPHENOL-STIMULATED ADENOSINE TRIPHOSPHATASE IN HUMAN BLOOD PLATELETS

1967 ◽  
Vol 15 (5) ◽  
pp. 267-272 ◽  
Author(s):  
VICTOR G. VETHAMANY ◽  
SYDNEY S. LAZARUS
Keyword(s):  
Enzyme Activity ◽  
Plasma Membrane ◽  
Human Blood ◽  
Adenosine Triphosphatase ◽  
Blood Platelets ◽  
Ultrastructural Localization ◽  
Human Platelets ◽  
Structural Localization ◽  
Adenosine Triphosphatase Activity ◽  
Human Blood Platelets

Fine structural localization of adenosine triphosphatase activity was studied in human platelets briefly fixed in cold formol calcium and then incubated in lead medium with added dinitrophenol. Under these conditions, the Mg++-dependent dinitrophenol-stimulated adenosine triphosphatase of platelet mitochondria was demonstrated, but neither granules nor plasma membrane showed enzyme activity.

scholarly journals Tracking of secretory phospholipase A2 enzyme activity levels from childhood to adulthood: a 21-year cohort

2019 ◽  
Vol 95 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Olivia Chung ◽  
Markus Juonala ◽  
Ziad Mallat ◽  
Nina Hutri-Kähönen ◽  
Jorma S.A. Viikari ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Phospholipase A2 ◽  
Activity Levels ◽  
Secretory Phospholipase A2 ◽  
Secretory Phospholipase

Modulation of plasma membrane H+-ATPase from oat roots by lysophosphatidylcholine, free fatty acids and phospholipase A2

1988 ◽  
Vol 74 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Michael Gjedde Palmgren ◽  
Marianne Sommarin ◽  
Peter Ulvlskov ◽  
Peter Leth Jorgensen
Keyword(s):  
Fatty Acids ◽  
Plasma Membrane ◽  
Phospholipase A2 ◽  
Free Fatty Acids

scholarly journals Pre-apoptotic Alterations in Hepatocytes of TNF α-treated Galactosamine-sensitized Mice

1998 ◽  
Vol 46 (10) ◽  
pp. 1175-1183 ◽  
Author(s):  
Sabine Angermüller ◽  
Gerald Künstle ◽  
Gisa Tiegs
Keyword(s):  
Enzyme Activity ◽  
Plasma Membrane ◽  
Cytochrome Oxidase ◽  
Oxidase Activity ◽  
Chromatin Condensation ◽  
Dna Strand Breaks ◽  
Strand Breaks ◽  
High Enzyme ◽  
Dna Strand ◽  
High Enzyme Activity

Tumor necrosis factor (TNF) induces apoptotic death of hepatocytes in the galactosamine (GalN)-sensitized mouse liver after 5 hr. In our study, the most remarkable sign of the early stage of apoptosis was the focal rupture of the outer mitochondrial membrane. Parts of the inner membrane extended through the gap of the outer membrane, whereas the rest of the inner membrane still formed the cristae. This feature appeared in hepatocytes before chromatin condensation. With the diaminobenzidine technique for localization of cytochrome oxidase activity, the reaction product was detectable by light and electron microscopy. Ten percent of the hepatocytes were apoptotic, with condensed chromatin and high enzyme activity, 37% were pre-apoptotic, without chromatin condensation but high enzyme activity, and 53% had neither condensed chromatin nor a remarkable reaction product of cytochrome oxidase activity. Fas (APO-1, CD95) molecules on the plasma membrane of hepatocytes increased and were represented immunohistochemically in cells without chromatin condensation. DNA strand breaks were also detectable before chromatin aggregation. The results of this study indicate that mitochondria play a pivotal role in pre-apoptotic hepatocytes, together with an increase of the Fas molecule on the plasma membrane and with the occurrence of DNA strand breaks in the nucleus.

scholarly journals Vitamin E potentiates arachidonate release and phospholipase A2 activity in rat heart myoblastic cells

1996 ◽  
Vol 319 (2) ◽  
pp. 385-391 ◽  
Author(s):  
Khai TRAN ◽  
Jason T WONG ◽  
Edmund LEE ◽  
Alvin C. CHAN ◽  
Patrick C. CHOY
Keyword(s):  
Enzyme Activity ◽  
Protein Kinase C ◽  
Vitamin E ◽  
Protein Kinase ◽  
Phospholipase A2 ◽  
Rat Heart ◽  
Lipid Vesicles ◽  
Ionophore A23187 ◽  
Kinase C ◽  
Arachidonate Release

Cytosolic phospholipase A2 (cPLA2) selectively catalyses the release of arachidonic acid from the sn-2 position of glycerophospholipids to produce prostaglandins and leukotrienes. In this study, vitamin E enrichment of rat heart myoblastic H9c2 cells caused an increase in the release of arachidonate during ionophore (A23187) stimulation. PLA2 activity in the cytosolic fraction was also enhanced but enzyme activity in the particulate fraction was not affected by this treatment. Immunoblotting analysis with a polyclonal anti-cPLA2 antibody showed an increased level of the enzyme in vitamin E-treated cells. Direct incorporation of vitamin E into lipid vesicles in the assay mixture resulted in modulation of enzyme activity in a biphasic manner. Pretreatment of cells with phorbol 12-myristate 13-acetate, a known activator of protein kinase C, synergistically potentiated the ionophore-induced arachidonate release in both the control and vitamin E-treated cells. However, vitamin E treatment by itself did not affect the protein kinase C activity, indicating that the vitamin E-induced activation of cPLA2 was independent of the protein kinase C cascade. Collectively, these results suggest that vitamin E potentiates arachidonate release through the direct and/or indirect modulation of cPLA2 activity.

scholarly journals Cytochemical evidence for the presence of phospholipids in epithelial tight junction strands.

1993 ◽  
Vol 41 (5) ◽  
pp. 649-656 ◽  
Author(s):  
F W Kan
Keyword(s):  
Plasma Membrane ◽  
Tight Junction ◽  
Phospholipase A2 ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Freeze Fracture ◽  
Fracture Face ◽  
Gold Particles ◽  
Pancreatic Cells ◽  
Specific Association

Previous freeze-fracture experiments using either glutaraldehyde-fixed and cryoprotected specimens or unfixed rapid-frozen samples led to the proposal that cylindrical strands of the tight junction (TJ) observed in freeze-fracture preparations are inverted cylindrical micelles made up of membrane lipids and, possibly, membrane proteins. However, no one has yet been able to directly label the structural fibrils of the TJ. To test the hypothesis that TJ strands observed on freeze-fracture preparations are composed at least partially of lipids, we have combined the phospholipase A2-gold and the fracture-label techniques for localization of phospholipids. Phospholipase A2, purified from bee venom, was adsorbed on gold particles and used for specific labeling of its substrate. Phospholipase A2-colloidal gold (PLA2-CG) complex was applied to freeze-fractured preparations of rat exocrine pancreatic cells and testicular Sertoli cells, both of which are known to have extensive TJ complexes on their plasma membranes. Fracture-label replicas of exocrine pancreatic cells revealed specific association of gold particles with TJ fibrils on the protoplasmic fracture-face of the plasma membrane. The majority of these gold particles were observed either directly on the top of the TJ fibrils or adjacent to these cylindrical structures. A high density of PLA2-CG labeling was also observed over the complementary exoplasmic fracture-face of the TJ complex. This intimate association of PLA2-CG labeling with the TJ is particularly evident in the Sertoli cell plasma membrane, where rows of gold particles were observed to be superimposed on parallel arrays of cylindrical strands of the TJ complex. The present findings provide direct cytochemical evidence to support the hypothesis that cylindrical TJ strands observed in freeze-fracture preparations contain phospholipids.

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