Protein and lipid composition of bovine milk-fat-globule membrane

Using mass spectrometry and other analytical methods, the proteins and lipids isolated from bovine milk-fat-globule membrane (MFGM) were characterised. The major MFGM protein composition consisted of xanthine oxidase, butyrophilin, adipophilin and periodic acid schiff 6/7. The minor proteins were polymeric immunoglobulin receptor protein, apolipoprotein E, apolipoprotein A1, 71 kDa heat-shock cognate protein, clusterin, lactoperoxidase, immunoglobulin heavy chain and peptidylprolyl isomerase A, actin, fatty acid-binding protein, cluster of differentiation 26 and mucin. The MFGM lipid component consisted predominantly of triglycerides (56%) and phospholipids (40.6%). The major fatty acids associated with the glycerol phospholipids were C16:0, C18:0, C18:1 and C18:2. Sphingomyelin had a high proportion of C20:0, C23:0, C24:1 and C24:0 fatty acids linked to the sphingoloid base. However, the sphingoloid base itself consisted predominantly of C16:1, C17:1 and C18:1 fatty acids. Small amounts of both lactosyl- and glucosyl-cerebrosides were found in the bovine MFGM sample and trace levels of lyso-phosphatidyl ethanolamine and lyso-phosphatidyl choline were detected.