One of the studies described is designed to determine the relative importance of mitochondrial acyltransferases in the determination of the ultimate positional distribution of fatty acids in membrane phosphoglycerides. An examination of the properties of mitochondrial and microsomal glycerol 3-phosphate and monoacylglycerol 3-phosphate acyl-transferase will be conducted in a variety of transplantable tumors and in cultured cells. The fatty acid composition and positional distribution in the major P-lipids of cellular and subcellular fractions will be determined and correlated with the properties of the acyltransferases in the mitochondria and microsomes of the cell. A second project will focus on the resolution and characterization of two fatty acid elongating systems in heart and liver mitochondria. The multienzyme systems will be purified and characterized with respect to their acyl-CoA primer specificity, the hydrogen donor(s), rate limiting step(s), and physical properties. Particular emphasis will be placed on the enzyme(s) and reductants required in the terminal step of the reaction sequence.