Some characteristics and cellular distribution of phospholipases A1 and A2 of rat testis.

The subcellular distribution and some properties of different phospholipases A of rat testis were studied using exogenous 1-acyl-2-[1-14C] oleoyl-sn-glycerol-3-phosphocholine as substrate. The presence of distinct phospholipases A: two phospholipases A1 with pH optimum at 3.0 and 7.4 respectively and a phospholipase A2 with pH optimum at 7.4 has been shown. The neutral phospholipases A1 and A2 have been further studied. The activities of phospholipases A1 and A2 with a pH optimum of 7.4 were greatly stimulated by sodium deoxycholate but were not affected by Triton X-100. The enzyme activities were slightly stimulated by Ca2+ but inhibited by EDTA at higher concentration. Studies using various effecters showed that the phospholipase A1 and A2 were, sensitive to sulfhydryl reagents and heat, insensitive to DIFP and cyclic nucleotides and completely inhibited by sodium dodecyl sulfate. Subcellular fractionation of testis homogenates and the subcellular distribution patterns of markers, marker enzymes and phospholipases A indicated that the phospholipases A1 and A2 with highest specific and relative specific activities were mainly localized in microsomal fractions.