title: Translocation of phospholipase A2 from cytosol to membranes in rat brain induced by calcium ions.
abstract: Phospholipase A2 (PLA2) activities were found in the cytosolic fractions of rat brain. Using the gel filtration chromatography, two major peaks of PLA2 activities were demonstrated: PLA2-H (200-500 kDa) and PLA2-L (100 kDa). PLA2-L was active at both neutral and alkaline pH and absolutely required Ca2+ for the activity, while the activity of PLA2-H was detected only at alkaline pH and independent of Ca2+. The activation of PLA2-L by Ca2+ was biphasic; the first observed at 1-100 microM Ca2+ and the second at 10 mM Ca2+. In the reconstitution system of partially purified PLA2-L and synaptosomal membranes from rat brain, PLA2-L associated with the membranes in a Ca2(+)-dependent manner. The association was completed within 5-10 min at 25 degrees C both at 10 microM and 1 mM Ca2+, though amount of PLA2-L translocated was dependent on Ca2+ concentrations. These results suggest that Ca2+ promotes the translocation of the cytosolic PLA2-L to membranes where phospholipids, substrate of PLA2, are present.
authors.affiliation: Department of Neuroscience, Osaka Bioscience Institute, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshihara
authors.forename: Y
authors.initials: Y
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D001692:Biological Transport; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D002845:Chromatography; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation; D008297:Male; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D051381:Rats; D011919:Rats, Inbred Strains; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
chemical_list: D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D002118:Calcium