Paracrystalline arrays of milk fat globule membrane-associated proteins as revealed by freeze-fracture

1982 ◽  
Vol 69 (10) ◽  
pp. 505-507 ◽  
Author(s):  
W. Buchheim
1978 ◽  
Vol 76 (3) ◽  
pp. 767-778 ◽  
Author(s):  
A Peixoto de Menezes ◽  
P Pinto da Silva

Membrane events during milk fat secretion were analyzed by freeze-fracture of the rat mammary gland. Two modes of milk fat secretion were observed: extrusion of fat droplets surrounded by a portion of the apical plasma membrane of the alveolar epithelial cells and, less frequently, release into the alveolar lumen of fat droplets contained in intracytoplasmic vacuoles. The extrusion process consists of two asynchronous events: clearing of membrane particles (probably including integral membrane proteins) and bulging of the apical plasma membrane. Most fat droplets are extruded with a bilayer membrane envelope (milk fat globule membrane) partially devoid of particles. The segregation of membrane particles may represent the onset of a process of structural degradation of the milk fat globule membrane.


Dairy ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 202-217
Author(s):  
Michele Manoni ◽  
Donata Cattaneo ◽  
Sharon Mazzoleni ◽  
Carlotta Giromini ◽  
Antonella Baldi ◽  
...  

Milk lipids are composed of milk fat globules (MFGs) surrounded by the milk fat globule membrane (MFGM). MFGM protects MFGs from coalescence and enzymatic degradation. The milk lipid fraction is a “natural solvent” for macronutrients such as phospholipids, proteins and cholesterol, and micronutrients such as minerals and vitamins. The research focused largely on the polar lipids of MFGM, given their wide bioactive properties. In this review we discussed (i) the composition of MFGM proteome and its variations among species and phases of lactation and (ii) the micronutrient content of human and cow’s milk lipid fraction. The major MFGM proteins are shared among species, but the molecular function and protein expression of MFGM proteins vary among species and phases of lactation. The main minerals in the milk lipid fraction are iron, zinc, copper and calcium, whereas the major vitamins are vitamin A, β-carotene, riboflavin and α-tocopherol. The update and the combination of this knowledge could lead to the exploitation of the MFGM proteome and the milk lipid fraction at nutritional, biological or technological levels. An example is the design of innovative and value-added products, such as MFGM-supplemented infant formulas.


2021 ◽  
pp. 106378
Author(s):  
Iolly Tábata Oliveira Marques ◽  
Fábio Roger Vasconcelos ◽  
Juliana Paula Martins Alves ◽  
Assis Rubens Montenegro ◽  
César Carneiro Linhares Fernandes ◽  
...  

1994 ◽  
Vol 1199 (1) ◽  
pp. 87-95 ◽  
Author(s):  
Naohito Aoki ◽  
Hidenori Kuroda ◽  
Miho Urabe ◽  
Yoshimi Taniguchi ◽  
Takahiro Adachi ◽  
...  

2002 ◽  
Vol 69 (4) ◽  
pp. 555-567 ◽  
Author(s):  
SUNG JE LEE ◽  
JOHN W. SHERBON

The effects of heat treatment and homogenization of whole milk on chemical changes in the milk fat globule membrane (MFGM) were investigated. Heating at 80 °C for 3–18 min caused an incorporation of whey proteins, especially β-lactoglobulin (β-lg), into MFGM, thus increasing the protein content of the membrane and decreasing the lipid. SDS-PAGE showed that membrane glycoproteins, such as PAS-6 and PAS-7, had disappeared or were weakly stained in the gel due to heating of the milk. Heating also decreased free sulphydryl (SH) groups in the MFGM and increased disulphide (SS) groups, suggesting that incorporation of β-lg might be due to association with membrane proteins via disulphide bonds. In contrast, homogenization caused an adsorption of caseins to the MFGM but no binding of whey proteins to the MFGM without heating. Binding of caseins and whey proteins and loss of membrane proteins were not significantly different between milk samples that were homogenized before and after heating. Viscosity of whole milk was increased when milk was treated with both homogenization and heating.


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