Molecular Species of Glycerolipids of Adenosine Triphosphatase and Sarcotubular Membranes of Rabbit Skeletal Muscle

The molecular species of choline, ethanolamine, serine, and inositol phosphatides and triglycerides were determined in purified adenosine triphosphatase and in the parent sarcotubular membranes of rabbit skeletal muscle. The total membrane and the adenosine triphosphatase were essentially identical in the composition of lipid classes and closely similar in patterns of molecular species of the corresponding phosphatides and triglycerides. The phosphatidylcholines were made up largely of the 1-palmitoyl 2-oleoyl and 1-palmitoyl 2-linoleoyl species. The ethanolamine phospholipids contained mainly the plasmalogens 1-palmitaldehyde 2-arachidonoyl and 1-stearaldehyde 2-arachidonoyl along with smaller amounts of the 1-palmitaldehyde 2-oleoyl and 1-palmitaldehyde 2-linoleoyl species. The phosphatidylinositols, which were analyzed along with about 10% phosphatidylserine, were characterized by large proportions of 1-stearoyl 2-arachidonoyl and smaller but significant proportions of the 1-stearoyl 2-oleoyl, 1-stearoyl 2-linoleoyl, and 1-stearoyl 2-eicosatrienoyl species. The triglycerides contained significant proportions of tripalmitin, triolein, and the isomeric palmitoyl oleoyl linoleins.The composition and molecular association of the fatty acids in these phosphatides showed significant differences from that of other tissues of the rabbit and other animals, as far as they have been analyzed, except for phosphatidylinositol, the structure of which was similar to that found elsewhere. The triglyceride composition was unusual in the high content of simple triglycerides.