The stimulatory effect of phosphatidylethanolamine on N-acylphosphatidylethanolamine-hydrolyzing phospholipase D (NAPE-PLD).
N-Acylphosphatidylethanolamine (NAPE)-hydrolyzing phospholipase D (NAPE-PLD) is a membrane-bound enzyme which releases the endocannabinoid anandamide and other bioactive N-acylethanolamines from their corresponding NAPEs in animal tissues. Our previous studies showed that NAPE-PLD solubilized from the membrane is remarkably stimulated by millimolar concentrations of Ca(2+) while the membrane-bound form is much less sensitive to Ca(2+). This finding suggested that certain membrane constituents diminished the stimulatory effect of Ca(2+). In the present studies, we examined the effects of membrane fractions from COS-7 cells and brain tissue on the purified recombinant rat NAPE-PLD, and found that heat-stable membrane component(s) dose-dependently activated NAPE-PLD up to 4.8-5.0 fold. In the presence of the membrane fractions, however, the stimulatory effect of Ca(2+) on the purified NAPE-PLD was considerably reduced. When it was examined if the membrane fractions can be replaced with various pure phospholipids, phosphatidylethanolamine activated NAPE-PLD up to 3.3 fold, which was followed by decrease in the stimulatory effects of Ca(2+) and several other divalent cations. These results suggest that membrane components including phosphatidylethanolamine keep the membrane-associated form of NAPE-PLD constitutively active.
Wang
Jun
J
Department of Biochemistry, Kagawa University School of Medicine, 1750-1 Ikenobe, Miki, Kagawa 761-0793, Japan.
Okamoto
Yasuo
Y
Tsuboi
Kazuhito
K
Ueda
Natsuo
N
D000818:Animals; D001921:Brain / Q000166:cytology / Q000187:drug effects; D001923:Brain Chemistry; D019556:COS Cells / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002522:Chlorocebus aethiops; D010714:Phosphatidylethanolamines / Q000494:pharmacology*; D010739:Phospholipase D / Q000378:metabolism*; D013997:Time Factors
D002118:Calcium; D010714:Phosphatidylethanolamines; D010739:Phospholipase D; C483858:phosphatidylethanolamine; C506062:Napepld protein, mouse