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Updated: Sep 29, 2026

Indirect Immunofluorescence on Frozen Sections of Mouse Mammary Gland
Published on: December 1, 2015
Milk lipid and protein traffic in mammary epithelial cells: joint and independent pathways
1Unité de Biologie Cellulaire et Moléculaire, INRA, Jouy-en-Josas, France. ollivier@jouy.inra.fr
Abstract:
In mammary epithelial cells, milk lipids and proteins are synthesised in the same compartment, the endoplasmic reticulum. Lipids, carried through the cytoplasm, associate with the apical membrane which then pinches off and releases the lipid globule. Proteins, carried through membrane compartments are released in the lumen after fusion of secretory vesicles with the apical membrane. These processes assure a relatively constant composition of milk but it is not known whether lipid and protein secretion are linked. The protein composition of the milk fat globule membrane and the stimulatory effects of prolactin and oxytocin on lipid and protein secretion suggest that these processes are coupled and co-regulated. However, it is possible to observe a dissociation between the formation and the secretion of the two constituents, during differentiation and in various experimental conditions, and this suggests that coupling is not strictly required.
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