Membranes of Mammary Gland. III. Lipid Composition of Golgi Apparatus from Rat Mammary Gland

Abstract

Purified Golgi apparatus fractions were obtained from mammary glands of lactating rats and were characterized morphologically and enzymologically. The lipid composition of the isolated fraction was determined and compared to rough endoplasmic reticulum and milk fat globule membranes. On a protein basis, Golgi apparatus and endoplasmic reticulum contained approximately the same amount of phospholipid. The Golgi apparatus fraction was rich in neutral lipid, most of which was due to triglyeeride-rich lipid droplets which adhered to the membranes. Golgi apparatus were intermediate between endoplasmic reticulum and milk fat globule membrane with respect to amounts of sphingomyelin, phosphatidyl choline, phosphatidyl inositol, and phosphatidyl ethanolamine. Golgi apparatus was also intermediate between the other two fractions with respect to membrane-bound sialic acid. The same fatty acids were found in both Golgi apparatus and milk fat globule membrane phospholipid classes. Results are compatible with the concept of Golgi apparatus-mediated cytomembrane differentiation. © 1972, American Dairy Science Association. All rights reserved.