The fat globule membranes of milk are derived from the apical plasma membrane of the mammary secretory cells. The nature of the membrane proteins, as isolated from @entity291 ' milk, has been studied by the use of discontinuous and continuous @entity214 -gel electrophoresis. Six methods of preparation of milk fat globule membrane suggested by various authors were tested; gel electrophoresis showed that five major bands were present, independent of the method of preparation. The apparent molecular masses of these proteins as determined on @entity214 -gels (15% T) were 167, 142, 64, 49 and 46 kDa, respectively. The 167 kDa band stained only with periodic acid- @entity9376 , while the 142 kDa band stained only with Coomassie blue; the last three bands stained with both. Delipidated membranes were extracted stepwise with water, 0.02 M @entity1219 and 0.6 M @entity1219 . The 64 kDa band appears to be nearly insoluble, while the bands of 142, 49 and 46 kDa are fractionated by this procedure. The resolution of all of these proteins by electrophoresis was superior to that achieved by molecular sieve chromatography, and so electrophoretic extraction was used to isolate the major proteins. @entity42817 derived proteins were used as markers. @entity535 compositions of the recovered proteins were obtained and are compared.

Identification of the milk fat globule membrane proteins. II. Isolation of major proteins from electrophoretic gels and comparison of their XXXX compositions.

@entity9376 :: ('MESH:C476677', 'Chemical') :: ['Schiff reagent'] @entity535 :: ('CHEBI:33704', 'Chemical') :: ['Amino acid'] @entity1219 :: ('CHEBI:26710', 'Chemical') :: ['NaCl'] @entity42817 :: ('MESH:C029038', 'Chemical') :: ['Dansyl chloride'] @entity291 :: ('9913', 'Species') :: ['cows'] @entity214 :: ('CHEBI:8984', 'Chemical') :: ['SDS']
@entity535 :: (CHEBI:33704,Chemical) :: ['amino acid']
