Comparative Phosphorylation Dynamics of Whey Proteins in Human Colostrum and Mature Milk: Implications for Infant Nutrition

Phosphorylation is an important post-translational modification that affects protein function and biological processes. In this study, label-free quantitative phosphoproteomics was employed to systematically identify the phosphorylated proteins and their phosphorylation sites in human colostrum (HC) and mature milk (HM) whey. In human colostrum, 30 phosphorylation sites on 24 phosphoproteins were identified, whereas in mature milk, 9 phosphorylation sites on 8 phosphoproteins were detected. Functional analysis revealed that the phosphorylated proteins in colostrum were primarily involved in immune regulation and inflammatory responses, while those in mature milk were more associated with metabolic regulation and immune homeostasis to meet the nutritional and physiological needs of infants during later stages of development. These findings highlight the dynamic adaptability of breast milk components according to the developmental needs of the infant, providing an important scientific basis for the design of stage-specific infant formula.