Quantitative phosphoproteomic analysis of fertilized egg derived from Tibetan and lowland chickens

In this study, immobilized metal affinity chromatography and ultra-high liquid chromatography tandem mass spectrometry were used to establish detailed phosphoproteomes of fertilized egg, and further quantitative compared those from Tibetan chicken and lowland chicken. A total of 138 phosphosites from 42 phosphoproteins were identified. Specifically, 103 phosphosites representing 41 phosphoproteins were detected in Tibetan chicken egg, and 125 sites in 40 phosphoproteins were found in lowland chicken egg; 47 phosphosites in 26 phosphoproteins were found in fertilized egg white, while 109 phosphosites in 24 phosphoproteins were identified in fertilized egg yolk. Thirty-one phosphoproteins carrying 83 phosphosites (12 phosphosites from 10 phosphoproteins in egg white and 52 sites from 17 proteins in egg yolk) showed significantly different phosphorylation between Tibetan and lowland chicken eggs, which were mainly involved in binding, catalysis, allergenic and cryoprotectant activities. Besides, several amino acid polymorphisms in ovalbumin and vittelligion-2 were detected, which might alter 3D structures and biofunctions. Our data recorded the egg phosphoprotein abundances and biological activities of two chicken species. These results provide a solid foundation to better understand the egg phosphoprotein characteristics, especially to explore the impacts of cross-species alteration of phosphorylation status on the structure, function and nutritional properties.