AUTHOR=Lu Jing , Zhang Wenyuan , Ma Changlu , Pang Xiaoyang , Dai Ying , Zhu Tong , Liu Jinqi , Xing Lina , Zhang Shuwen , Lv Jiaping TITLE=Changes in glycosylated proteins in colostrum and mature milk and their implication JOURNAL=Frontiers in Nutrition VOLUME=10 YEAR=2023 URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1161310 DOI=10.3389/fnut.2023.1161310 ISSN=2296-861X ABSTRACT=Introduction

Glycosylation is one of the essential post-translational modifications that influences the function of milk proteins.

Methods

In the present study, 998 proteins and 764 glycosylated sites from 402 glycoproteins were identified in human milk by TMT labeling proteomics. Compared to human milk proteins, the glycoproteins were mainly enriched in cell adhesion, proteolysis, and defense/immune process.

Results

The abundance of 353 glycosylated sites and their 179 parent proteins was quantified. After normalization to their parent protein’s abundance, 78 glycosylated sites in 56 glycoproteins and 10 glycosylated sites in 10 glycoproteins were significantly higher in colostrum and mature milk, respectively. These changed glycoproteins were mainly related to host defense. Intriguingly, one glycosylated site (Asp144) in IgA and two glycosylated sites (Asp38 and Asp1079) in tenascin are significantly upregulated even though their protein abundance was downregulated during lactation.

Discussion

This study helps us figure out the critical glycosylated sites in proteins that might influence their biological function in an unbiased way.