title: Phosphatidylserine biosynthesis in mitochondria from Ehrlich ascites tumor cells.
abstract: 1. Isolated mitochondria of Ehrlich ascites tumor cells incorporated [14C]serine into phosphatidylserine and partly into its decarboxylation product, phosphatidylethanolamine, while phosphatidylserine was the sole product with microsomes. 2. The incorporation of [14C]serine into mitochondrial phospholipids was stimulated by Ca2+ which indicated the operation of the Ca2+-dependent base-exchange mechanism, virtually absent in mammalian tissue mitochondria. The finding cannot be attributed to microsomal contamination. 3. The incorporation of [14C]serine into mitochondrial phospholipids was also stimulated by ATP, both in the presence and in the absence of calcium-complexing agents. The stimulation by ATP was insensitive to penicillin and streptomycin, thus pointing that this process was not of bacterial origin. 4. The latter process was further stimulated by phosphatidic acid and phosphatidic acid precursors, but not by CDP diacylglycerol. 32P from neither [gamma-32P]ATP nor [32P]phosphatidic acid was incorporated into phosphatidylserine in the presence of CTP and L-serine. The release of [14C]CMP from [14C]CDP diacylglycerol was not stimulated by l-serine. 5. It is concluded that [14C]serine incorporation into mitochondrial phospholipids by ATP-dependent process does not fit to any of the pathways of phopholipid biosynthesis described so far.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000494:pharmacology; D002286:Carcinoma, Ehrlich Tumor / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009374:Neoplasms, Experimental / Q000378:metabolism; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010718:Phosphatidylserines / Q000096:biosynthesis*
chemical_list: D010713:Phosphatidylcholines; D010718:Phosphatidylserines; D000255:Adenosine Triphosphate; D002118:Calcium