Comparison and analysis for exclusively expressed sites of milk fat globule membrane phosphoproteins between human and bovine milk based on label-free phosphoproteomic

Milk fat globule membrane (MFGM) proteins, which serve as nutritional components in infant formulas, have garnered increasing attention. This study investigates the exclusively expressed MFGM protein phosphorylation of human milk (HM) and bovine milk (BM) using label-free phosphoproteomics. The results indicate that 188 exclusively phosphorylated sites were identified on 105 phosphoproteins in HM, while 267 exclusively phosphorylated sites were identified on 149 phosphoproteins in BM. Osteopontin and Perilipin-2 demonstrated the highest number of phosphorylation sites in HM and BM. Bioinformatics function analysis revealed that phosphorylated proteins in human MFGM were primarily involved in development and immune-related functions, whereas phosphorylated proteins in bovine MFGM were predominantly associated with signal response functions. Thirteen key MFGM proteins were identified by screening. Notably, Butyrophilin subfamily 1 member A1 (BTN1A1), Complement C3 (C3), and Lactadherin (MFGE8) were contributed to accurately mimic. This research is instrumental in bridging the disparity between HM and BM-based formulas, as well as elucidating the role of MFGM protein phosphorylation in infant formula milk powder industry.