Milk-fat globule membranes: chemical composition and phosphoesterase activities during lactation

1977 ◽  
Vol 44 (3) ◽  
pp. 483-493 ◽  
Author(s):  
Teresa Diaz-Mauriño ◽  
M. Nieto
Keyword(s):  
Amino Acid ◽  
Chemical Composition ◽  
Amino Acid Analysis ◽  
Milk Fat ◽  
Stage Of Lactation ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes ◽  
Carbohydrate Contents ◽  
Acid Phosphomonoesterase

SummaryThe morphology, protein and glycoprotein composition, amino-acid analysis, phospholipid and carbohydrate contents and 3 phosphoesterase activities of the milk-fat globule membranes were studied in 4 cows during their whole period of lactation. No differences were found in the morphology and the overall chemical composition. However, glycoprotein composition varied with the cow and, for each cow, with the stage of lactation. The differences were more marked for membranes obtained from colostrum. Acid phosphomonoesterase was practically unchanged during the whole period of lactation, while alkaline phosphomonoesterase and phosphodiesterase increased as lactation proceeded.

scholarly journals Isolation and characterization of two individual glycoprotein components from human milk-fat-globule membranes

1982 ◽  
Vol 207 (1) ◽  
pp. 37-41 ◽  
Author(s):  
A Imam ◽  
D J Laurence ◽  
A M Neville
Keyword(s):  
Human Milk ◽  
Milk Fat ◽  
Sodium Dodecyl ◽  
Membrane Glycoproteins ◽  
Lectin Affinity Chromatography ◽  
Isolation And Characterization ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes ◽  
Human Milk Fat

Two individual glycoprotein components from human milk-fat-globule membranes (MFGM) has been purified by selectively extracting the membrane glycoproteins followed by lectin affinity chromatography and gel filtration on Sephadex G-200 in the presence of protein-disaggregating agents. The purified glycoprotein components, termed ‘epithelial-membrane glycoprotein’ (EMGP-155 and EMGP-39) have estimated molecular weights of 155 000 and 39 000 respectively, and yield a single band under reducing conditions on sodium dodecyl sulphate/polyacrylamide gel. EMGP-155 and EMGP-39 contain 21.0% and 7.0% carbohydrate by weight, with fucose (13.5%, 12.4%), mannose (3.7%, 6.2%), galactose (28.5%, 22.6%), N-acetylglucosamine (17.8%, 7.4%) and sialic acid (36.4%, 51.4%) of the carbohydrate moiety respectively. For both the glycoprotein components, aspartic and glutamic acid and serine are the major amino acid residues.

Reactions of Monoclonal Antibodies against Human Milk Fat Globule Membranes with Embryonal Tissue

1984 ◽  
pp. 1021-1024 ◽  
Author(s):  
U. KOLDOVSKY ◽  
U. WARGALLA ◽  
J. HILKENS ◽  
J. TAYLOR-PAPADIMITRIOU ◽  
PH. HAGEMANN ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Human Milk ◽  
Milk Fat ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes ◽  
Human Milk Fat

scholarly journals BIOCHEMICAL AND MORPHOLOGICAL COMPARISON OF PLASMA MEMBRANE AND MILK FAT GLOBULE MEMBRANE FROM BOVINE MAMMARY GLAND

1970 ◽  
Vol 44 (1) ◽  
pp. 80-93 ◽  
Author(s):  
T. W. Keenan ◽  
D. James Morré ◽  
Diane E. Olson ◽  
W. N. Yunghans ◽  
Stuart Patton
Keyword(s):  
Fatty Acid Composition ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Acid Composition ◽  
Milk Fat ◽  
Major Protein ◽  
Thin Sections ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes

Purified plasma membrane fractions from lactating bovine mammary glands and membranes of milk fat globules from the same source were similar in distribution and fatty acid composition of phospholipids. The sphingomyelin content of the phospholipid fraction of both membranes was higher than in these fractions from other cell components, ß-carotene, a constituent characteristic of milk fat, was present in the lipid fraction of the plasma membrane. Cholesterol esters of plasma membrane were similar in fatty acid composition to those of milk fat globule membranes. Disc electrophoresis of either membrane preparation on polyacrylamide gels revealed a single major protein component characteristic of plasma membrane from other sources. Distinct morphological differences between plasma membrane and milk fat globule membranes were observed in both thin sections and in negatively stained material. Plasma membrane was vesicular in appearance while milk fat globule membranes had a platelike aspect. These observations are consistent with derivation of fat globule membrane from plasma membrane accompanied by structural rearrangement of membrane constituents.

scholarly journals Redox constituents in milk fat globule membranes and rough endoplasmic reticulum from lactating mammary gland.

1977 ◽  
Vol 73 (1) ◽  
pp. 223-241 ◽  
Author(s):  
E D Jarasch ◽  
G Bruder ◽  
T W Keenan ◽  
W W Franke
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammary Gland ◽  
Low Temperatures ◽  
Milk Fat ◽  
Cytochrome B5 ◽  
Alpha Band ◽  
Lactating Mammary Gland ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes

Milk fat globule membranes (MFGM) and rough endoplasmic reticulum (RER) membranes were isolated from milk and lactating mammary gland from the cow and were characterized by biochemical and electron microscope methods in terms of gross composition (proteins, phospholipids, neutral lipids, cholesterol, RNA, and DNA) and purity. Both fractions contained significant amounts of a b-type cytochrome with several properties similar to those of cytochrome b5 from liver, as well as a rotenone-insensitive NADH- and NADPH-cytochrome c reductase. The b-type cytochrome content in the apical plasma membrane-derived MFGM was of the same order of magnitude as it was in RER membranes. It was characterized by a high resistance to extraction by low- and high-salt concentrations and nonionic detergents. MFGM contained much more flavin and much higher activities of xanthine oxidase than the RER membranes. The same redox components were found in MFGM and mammary RER from women, rats, mice, and goats, but in absolute contents great differences between the species were noted. The cytochromes described here differed from liver cytochrome b5 in some spectral properties. The alpha-band of the reduced hepatic cytochrome b5 is asymmetric with a maximum at 555 nm that is split into two distinct peaks at low temperatures. The alpha-band of the b-type cytochromes from MFGM and mammary RER appears as one symmetrical peak at about 560 nm that is not split at low temperatures. When treated with cyanide, MFGM and mammary microsomes showed difference spectra of a reduced b-type cytochrome. Under the same conditions, liver microsomes gave a completely different spectrum. These findings demonstrate the presence of a b-type cytochrome and associated redox enzymes in MFGM, i.e., a derivative of the apical cell surface membrane that is regularly used for envelopment of the milk fat globule during secretion.

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