scholarly journals Freeze-fracture observations of the lactating rat mammary gland. Membrane events during milk fat secretion.

1978 ◽  
Vol 76 (3) ◽  
pp. 767-778 ◽  
Author(s):  
A Peixoto de Menezes ◽  
P Pinto da Silva
Keyword(s):  
Plasma Membrane ◽  
Mammary Gland ◽  
Milk Fat ◽  
Freeze Fracture ◽  
Apical Plasma Membrane ◽  
Milk Fat Globule Membrane ◽  
Membrane Particles ◽  
Milk Fat Globule ◽  
Rat Mammary Gland ◽  
Fat Globule

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.

PROTEOME OF MILK FAT GLOBULE MEMBRANE AND MAMMARY GLAND TISSUE IN GOAT FED DIFFERENT LIPID SUPPLEMENTATION

2021 ◽  
pp. 106378
Author(s):  
Iolly Tábata Oliveira Marques ◽  
Fábio Roger Vasconcelos ◽  
Juliana Paula Martins Alves ◽  
Assis Rubens Montenegro ◽  
César Carneiro Linhares Fernandes ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Milk Fat ◽  
Milk Fat Globule Membrane ◽  
Mammary Gland Tissue ◽  
Gland Tissue ◽  
Milk Fat Globule ◽  
Lipid Supplementation ◽  
Fat Globule

scholarly journals Proteolysis of Milk Fat Globule Membrane Proteins in Preterm Milk: A Transient Phenomenon with a Possible Biological Role?

2008 ◽  
Vol 21 (4) ◽  
pp. 959-967 ◽  
Author(s):  
M.G. Giuffrida ◽  
M. Cavaletto ◽  
C. Lamberti ◽  
G. Dellavalle ◽  
C. Fabris ◽  
...  
Keyword(s):  
Mammary Gland ◽  
Membrane Proteins ◽  
Preterm Delivery ◽  
Preterm Infants ◽  
Milk Fat ◽  
Biological Role ◽  
Transient Phenomenon ◽  
Milk Fat Globule Membrane ◽  
Milk Fat Globule ◽  
Fat Globule

Milk fat globule membrane (MFGM) proteins constitute a milk fraction currently of great interest, as they appear to significantly contribute to milk protective role. We investigated these proteins in human preterm colostrum and milk. For the former we found a peculiar 2-DE pattern, with a spot concentration at low molecular weight, which mass spectrometry analysis showed to be fragments belonging to some MFGM proteins with a well-known biological and especially immunological role: lactadherin, membrane-associated lactoferrin, butyrophilin, clusterin and heavy-chain immunoglobulin. Since we were able to rule out protease activity after specimen collection, we hypothesize the localization of the proteolytic enzymes in the alveolar cell membranes of the mammary gland. This mechanism is probably under hormonal control and the unexpected advent of preterm delivery would not allow hormonal conditions typical of lactation to occur immediately, causing a delay in enzymatic inhibition. This hypothesis is supported by some of our results, picturing a peculiar transient phenomenon of adaptation of the mammary-gland-membrane proteins after preterm delivery. Further studies will be required to verify whether the presence of protein fragments exerts a specific biological and immuno-defensive role in preterm infants, thus adding evidence to the outstanding biological role and benefits of mother's own milk in feeding preterm infants.

scholarly journals The endoplasmic reticulum and casein-containing vesicles contribute to milk fat globule membrane

2016 ◽  
Vol 27 (19) ◽  
pp. 2946-2964 ◽  
Author(s):  
Edith Honvo-Houéto ◽  
Céline Henry ◽  
Sophie Chat ◽  
Sarah Layani ◽  
Sandrine Truchet
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Milk Fat ◽  
Milk Secretion ◽  
Milk Fat Globule Membrane ◽  
Fat Globules ◽  
Milk Fat Globules ◽  
Milk Fat Globule ◽  
Fat Globule ◽  
Milk Fat Globule Membranes

During lactation, mammary epithelial cells secrete huge amounts of milk from their apical side. The current view is that caseins are secreted by exocytosis, whereas milk fat globules are released by budding, enwrapped by the plasma membrane. Owing to the number and large size of milk fat globules, the membrane surface needed for their release might exceed that of the apical plasma membrane. A large-scale proteomics analysis of both cytoplasmic lipid droplets and secreted milk fat globule membranes was used to decipher the cellular origins of the milk fat globule membrane. Surprisingly, differential analysis of protein profiles of these two organelles strongly suggest that, in addition to the plasma membrane, the endoplasmic reticulum and the secretory vesicles contribute to the milk fat globule membrane. Analysis of membrane-associated and raft microdomain proteins reinforces this possibility and also points to a role for lipid rafts in milk product secretion. Our results provide evidence for a significant contribution of the endoplasmic reticulum to the milk fat globule membrane and a role for SNAREs in membrane dynamics during milk secretion. These novel aspects point to a more complex model for milk secretion than currently envisioned.

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