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Updated: Aug 7, 2026
11:13
Indirect Immunofluorescence on Frozen Sections of Mouse Mammary Gland
Published on: December 1, 2015
Butyrophilin controls milk fat globule secretion
Horst Robenek1, Oliver Hofnagel2, Insa Buers2
1*Leibniz-Institute for Arteriosclerosis Research, University of Münster, 48149 Münster, Germany; robenek@uni-muenster.de.
Summary
Milk fat globule secretion involves butyrophilin interactions within the mammary epithelial cell. This study revises the mechanism, proposing direct butyrophilin interactions control secretion, not xanthine oxidoreductase complexes.
Area of Science:
- Cell Biology
- Biochemistry
- Mammary Gland Biology
Background:
- Milk fat globule secretion is crucial for lactation.
- Previous models proposed xanthine oxidoreductase complexes mediate secretion.
- Adipophilin was thought to bind these complexes within secretory granules.
Purpose of the Study:
- To elucidate the precise molecular mechanism of milk fat globule secretion.
- To re-evaluate the roles of butyrophilin, xanthine oxidoreductase, and adipophilin in secretion.
Main Methods:
- Freeze-fracture immunocytochemistry was employed.
- Localization of key proteins within mammary epithelial cells and milk fat globules was analyzed.
Main Results:
- Butyrophilin was found in distinct locations from previous inferences.
- Butyrophilin forms concentrated ridges in the residual plasma membrane of the globule envelope.
- These ridges align with butyrophilin labeling in the globule monolayer.
Conclusions:
- The proposed mechanism involves direct interactions between plasma membrane butyrophilin and butyrophilin in the secretory granule monolayer.
- This interaction, rather than xanthine oxidoreductase complex binding to adipophilin, controls milk fat globule secretion.
- A revised model for milk fat globule secretion is presented.
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