The @entity19 macrophage (M phi) cell line, P388D1, was employed as a source of M phi phospholipases in order to characterize the enzymatic properties and subcellular localization of these enzymes because of their importance for prostaglandin biosynthesis. Phospholipase activity was assessed with @entity4747 ( @entity4748 ) as substrate. Phospholipases were characterized with respect to divalent cation dependence, pH optima, and localization in subcellular compartments using linear @entity969 gradients. By these criteria a number of different phospholipases were identified. Most importantly, a single @entity141 -dependent activity with a pH optimum of 8.8 was identified in membrane-rich fractions (plasma membrane, mitochondria, and endoplasmic reticulum) and could be clearly separated from the remaining activities, which are @entity141 independent and exhibit pH optima of 7.5, 5.1, and 4.2. The phospholipases with acidic pH optima may be associated with subcellular components containing lysosomal enzymes and both phospholipase A1 and phospholipase A2 activities are observed. In contrast, the phospholipase activity with a pH optimum of 7.5 sediments with the cytosolic proteins and is inhibited by 5 mM @entity141 . No significant phospholipase C activity was detected in assays performed with or without added @entity141 at pH's 4.2, 5.1, 7.5, or 8.8 using @entity4748 as substrate. However, the @entity19 cells do contain a lysophospholipase that is at least 20 times more active than the phospholipase A activities identified. Its presence must be taken into account in evaluating the positional specificities and properties of the macrophage phospholipases.

Phospholipase activities of the XXXX macrophage-like cell line.

@entity19 :: ('10090', 'Species') :: ['P388D1', 'murine'] @entity4748 :: ('CHEBI:40265', 'Chemical') :: ['DPPC'] @entity969 :: ('MESH:D013395', 'Chemical') :: ['sucrose'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity4747 :: ('MESH:D015060', 'Chemical') :: ['dipalmitoylphosphatidylcholine']
@entity19 :: (10090,Species) :: ['P388D1']
