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Regional Distribution, Ontogeny, Purification, and Characterization of the Ca 2+ ‐Independent Phospholipase A 2 from Rat Brain
Author(s) -
Yang HsiuChiung,
Mosior Marian,
Ni Binhui,
Dennis Edward A.
Publication year - 1999
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1999.0731278.x
Subject(s) - phosphatidylcholine , phospholipase a2 , vesicle , biochemistry , biology , phosphatidylinositol , phospholipase c , phospholipid , arachidonic acid , isozyme , phospholipase , microbiology and biotechnology , enzyme , membrane , signal transduction
: We purified an 80‐kDa Ca 2+ ‐independent phospholipase A 2 (iPLA 2 ) from rat brain using octyl‐Sepharose, ATP‐agarose, and calmodulin‐agarose column chromatography steps. This procedure gave a 30,000‐fold purification and yielded 4 μg of a near‐homogeneous iPLA 2 with a specific activity of 4.3 μmol/min/mg. Peptide sequences of the rat brain iPLA 2 display considerable homology to sequences of the iPLA 2 from P388D 1 macrophages, Chinese hamster ovary cells, and human B lymphocytes. Under optimal conditions, the iPLA 2 revealed the following substrate preference toward the fatty acid chain in the sn ‐2 position of phosphatidylcholine : linoleoyl > palmitoyl > oleoyl > arachidonoyl. The rat brain iPLA 2 also showed a head group preference for choline ≥ ethanolamine ≫ inositol. The iPLA 2 is inactivated when exposed to pure phospholipid vesicles. The only exception is vesicles composed of phosphatidylcholine and phosphatidylinositol 4,5‐bisphosphate. Studies on the regional distribution and ontogeny of various phospholipase A 2 (PLA 2 ) types in rat brain indicate that the iPLA 2 is the dominant PLA 2 activity in the cytosolic fraction, whereas the group IIA secreted PLA 2 is the dominant activity in the particulate fraction. The activities of these two enzymes change during postnatal development.