A High-Throughput Comparative Proteomics of Milk Fat Globule Membrane Reveals Breed and Lactation Stages Specific Variation in Protein Abundance and Functional Differences Between Milk of Saanen Dairy Goat and Holstein Bovine.

Wei Jia,Rong Zhang,Zhenbao Zhu,Lin Shi

doi:10.3389/fnut.2021.680683

Wei Jia, Rong Zhang + Show 2 more

Open Access

https://doi.org/10.3389/fnut.2021.680683

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Abstract

Large variations in the bioactivities and composition of milk fat globule membrane (MFGM) proteins were observed between Saanen dairy goat and Holstein bovine at various lactation periods. In the present study, 331, 250, 182, and 248 MFGM proteins were characterized in colostrum and mature milk for the two species by Q-Orbitrap HRMS-based proteomics techniques. KEGG pathway analyses displayed that differentially expressed proteins in colostrum involved in galactose metabolism and an adipogenesis pathway, and the differentially expressed proteins in mature milk associated with lipid metabolism and a PPAR signaling pathway. These results indicated that the types and functions of MFGM proteins in goat and bovine milk were different, and goat milk had a better function of fatty acid metabolism and glucose homeostasis, which can enhance our understanding of MFGM proteins in these two species across different lactation periods, and they provide significant information for the study of lipid metabolism and glycometabolism of goat milk.

Highlights

Milk fat is an important fraction of milk synthesized by the endoplasmic reticulum of mammary epithelial cells
45 milk fat globule membrane (MFGM) proteins, coupled with cream fractions, were identified in four milk groups, including the complement component 3, fatty acid synthase, sodiumdependent phosphate transport protein 2B, and pericentrin, indicating that goat milk was a substitute for bovine milk to some extent in the research and development of infant milk powder and functional food, and providing an orientation for the further functional development of goat milk
The results of Principal component analysis (PCA), partial least squares regression-discriminant analysis (PLS-DA), and VIP analysis found out that nucleobindin1 (NUCB1), folate receptor alpha (FOLR1), vitamin D-binding protein (GC), thrombospondin-1 (THBS1), and beta-1,4galactosyltransferase 1 (B4GALT1), with the lower abundance in goat mature milk than in other three milk groups, can be used as markers to distinguish the four milk groups

Summary

Introduction

Milk fat is an important fraction of milk synthesized by the endoplasmic reticulum of mammary epithelial cells. It is a droplet composed of a neutral triglyceride core wrapped by a thin trilayered membrane. Milk fat is mainly composed of cholesterol, polar lipids, neutral lipids, and a protein group from the membrane and cytoplasmic crescents [1, 2]. Protein, which accounts for 22–70% of the MFGM matter, provides protection to core milk fat and has a series of biological functions, such as preventing infection of enteric pathogens, promoting immune and neurological functions, as well as the development of newborns [3, 4].

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