Some Properties of Membrane-Bound Phospholipases A2

Purification and characterization of nuclear alkaline phospholipase A2 in rat ascites hepatoma cells

“…In mammalian cells, PLA2 has been found in various subcellular fractions, plasma membrane [1,2], Golgi membrane [3], microsome [4], mitochondria [5], lysosome [6], and cytosol [7,8]. To date, little information concerning nuclei is available, even inclusive of our previous report [9].…”

“…The former two are often termed 'secretory PLA2'. In the last few years, the secretory PLA2 species, especially group II PLA2, have been found in the particulate fractions of many cells and tissues in spite of the presence of a typical signal sequence as a secretory enzyme in its molecule [5,[10][11][12]. Further, the subcellular localization of group II PLA2 seems to be various in tissues and cells, i.e.…”

Some aspects of rat platelet and serum phospholipase A2 activities

“…In addition, the enzyme eluted from Matrex gel blue A with a high salt buffer, and in this respect behaved like phospholipase A, from rat liver mitochondria [33], and cobra venom [31]. Likewise, the behaviour of the monomeric platelet phospholipase A, on an affinity column, i.e., binding in the presence of Ca2+ and elution with buffers containing EDTA, is completely comparable to that of phospholipase A, activities from cobra venom [29,40], porcine pancreas [29], sheep erythrocytes [32] and rat liver mitochondria [29]. A, activity peak.…”

“…Compared to the applied activity, a recovery of about 150% was found. Chromatography of the Matrex gel blue A fraction, after concentration and dialysis, on an affinity column as previously described [29], showed that enzymatic activity was bound to the immobilized ligand in the presence of Ca2+ and that it could be eluted with buffers containing EDTA (Fig. 5).…”

“…Rat platelet phospholipase A z behaved in an unusual manner in these experiments, in that it eluted in the void volume of a Sephadex G-100 column. Without exception, Ca"-dependent phospholipases A z, including those from pancreas [28,29], snake venoms [30,31], sheep erythrocytes [32], rat liver mitochondria [33] and rabbit platelets [34], exhibit molecular weights of about 15 kDa. To clarify the unusual behaviour of rat platelet phospholipase A>, we initiated experiments to partially purify the phospholipase A, activity from rat platelet lysates and from rat serum and to further characterize the activating factor.…”