The Magnesium-Dependent Incorporation of Serine into the Phospholipids of Mitochondria Isolated from the Developing Flight Muscle of the African Locust Locusta migratoria

1 A magnesium-dependent, adenosine triphosphate-stimulated incorporation of l-[U14C]-serine into the phospholipids of mitochondria isolated from the developing flight muscle of Locusta migratoria was studied. 2 Serine phosphoglyceride is the major phospholipid component into which the serine is incorporated. Significant incorporation into ethanolamine phosphoglyceride is also observed. 3 Data is presented indicating that neither contaminating microsomes nor bacteria contribute to the incorporation. 4 Optimal conditions for serine incorporation include appropriate concentrations of phosphate, Mg++, KCl and adenosine triphosphate. The latter can be provided either via respiratorychain phosphorylation or exogenously. Hypothetical high-energy intermediates of oxidative phosphorylation are not obligatory. 5 The extent of serine incorporated into the flight muscle mitochondria in vitro can be correlated with the development of the adult locust. 6 The results are compared with those obtained in similar mammalian systems. The potential advantages of this system for studying both membrane development and biogenesis of mitochondria is discussed.