Studies on the brush border membrane on mouse duodenum: lipids

Lipids were extracted from purified mouse duodenal brush border membranes. Lipid: protein ratios in different membrane preparations varied from 0.58 to 0.68. Both the chloroform and non-chloroform phases were quantitatively analysed for lipids. Chloroform extracts were composed of cholesterol, triglycerides and phospholipids. The major neutral lipid was cholesterol. Rechromatrography of the phospholipid spot showed sphingomyelin (7.9%), phosphatides of ethanolamine (61.7%), inositol (14.2%) and serine (16.2%). The average molar ratio of cholesterol to phospholipid was 1.39. Lipids in the non-chloroform phase were all glycosylated, being cerebrosides (69.3%), cerebroside sulphates (28.8%) and galgliosides (1.9%). Overal membrane lipid composition was neutral lipid 24%, phospholipid 33%, and glycolipid 43%.