Document Detail

Recognition of acidic phospholipase A2 activity in plasma membranes of resident peritoneal macrophages.
MedLine Citation:
PMID:  3137407     Owner:  NLM     Status:  MEDLINE    
Phospholipase (PLase) activities in the plasma membrane of guinea pig peritoneal macrophages were studied, as these enzymes having such activity may be candidates for the release of arachidonic acid (AA) from phosphatidylcholine (PC). An AA release system operating at acidic pH was identified in the macrophage plasma membrane and characterized. This membrane-bound acidic PLase A2 had an optimum pH at 4.5, and enzyme activation was observed in Ca++-free medium; but the maximum activity was found at 0.5 mM Ca++ concentration. The Km value for PC of acidic PLase A2 was 4.2 microM, and a Michaelis-Menten relationship was evident. Calcium might act as a cofactor at some intermediate step during the activation of acidic PLase A2 in light of the uncompetitive manner of Ca++ action. Furthermore, the release of [3H]-AA from preradiolabelled macrophage plasma membranes occurred with the addition of Ca++ at pH 4.5. These data suggest that the acid PLase A2 is a component of the plasma membrane and is not due to lysosomal contamination since membrane-bound acidic PLase A2 properties are opposite to those found for lysosomal PLase A2.
Y Shibata; Y Abiko; H Ohno; T Araki; H Takiguchi
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Life sciences     Volume:  43     ISSN:  0024-3205     ISO Abbreviation:  Life Sci.     Publication Date:  1988  
Date Detail:
Created Date:  1988-10-07     Completed Date:  1988-10-07     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0375521     Medline TA:  Life Sci     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  889-96     Citation Subset:  IM    
Department of Biochemistry, Nihon University School of Dentistry, Matsudo, Japan.
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MeSH Terms
Arachidonic Acid
Arachidonic Acids / metabolism
Calcium / pharmacology
Cell Membrane / enzymology
Fatty Acids / metabolism
Guinea Pigs
Hydrogen-Ion Concentration
Macrophages / enzymology*
Peritoneal Cavity / cytology
Phospholipases / metabolism*
Phospholipases A / metabolism*
Phospholipases A2
Substrate Specificity
Reg. No./Substance:
0/Arachidonic Acids; 0/Fatty Acids; 506-32-1/Arachidonic Acid; 7440-70-2/Calcium; EC 3.1.-/Phospholipases; EC 3.1.1.-/Phospholipases A; EC A2

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