Detection and subcellular localization of rabbit platelet phospholipase A2 which preferentially hydrolyzes an arachidonoyl residue.
Like rat platelets, rabbit platelets contain a secretory 14-kDa group II phospholipase A2 [Mizushima, H., Kudo, I., Horigome, K., Murakami, M., Hayakawa, M., Kim, D.K., Kondo, E., Tomita, M., & Inoue, K. (1989) J. Biochem. 105, 520-525]. The present study was undertaken to determine whether or not, in addition to that of the 14-kDa group II enzyme, rabbit platelets exhibit another phospholipase A2 activity. A rabbit platelet soluble fraction was prepared by sonication and centrifugation. When this soluble fraction was subjected to heparin-Sepharose column chromatography, phospholipase A2 activity was detected in both heparin-binding and heparin-non-binding fractions. The activity detected in the heparin-binding fraction appeared to belong to the secretory 14-kDa phospholipase A2, because it bound to anti-human 14-kDa group II phospholipase A2 monoclonal antibody. The activity found in the heparin-non-binding fraction did not appreciably react with the same antibody. When platelets were gently disrupted by the nitrogen cavitation method, the heparin-non-binding activity was mainly recovered in the platelet cytosolic fraction. The heparin-non-binding phospholipase A2 hydrolyzed a phospholipid bearing an arachidonoyl residue at the sn-2 position more effectively than one with a linoleoyl residue. The biochemical features of the activity observed in the heparin-non-binding fraction generally resembled those of human platelet soluble phospholipase A2 [Kim, D.K., Kudo, I., & Inoue, K. (1988) J. Biochem. 104, 492-494].(ABSTRACT TRUNCATED AT 250 WORDS)
Kim
D K
DK
Faculty of Pharmaceutical Sciences, University of Tokyo.
Kudo
I
I
Fujimori
Y
Y
Mizushima
H
H
Masuda
M
M
Kikuchi
R
R
Ikizawa
K
K
Inoue
K
K
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001095:Arachidonic Acids / Q000378:metabolism*; D001792:Blood Platelets / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D002498:Centrifugation; D002846:Chromatography, Affinity; D003600:Cytosol / Q000201:enzymology; D006868:Hydrolysis; D010741:Phospholipases A / Q000276:immunology / Q000378:metabolism*; D054467:Phospholipases A2; D011817:Rabbits
D000911:Antibodies, Monoclonal; D001095:Arachidonic Acids; D010741:Phospholipases A; D054467:Phospholipases A2