Comparative Proteomic Analysis Of Whey Protein And Fat Globule Membrane Protein Between River-typed Buffaloes And Holstein Cows

Buffalo milk is known as "the king of milk,treasures in milk" and has high nutritional value and economic value.In this study,iTRAQ quantitative proteomic technology was used to perform differential proteomic studies on whey protein and fat globule membrane proteins between river-typed buffaloes and Holstein cows in subtropical regions.Which contributes us to understand the differences between buffalo milk and cow milk in the protein level and lays the foundation for the related molecular mechanisms.The experimental results are as follows:(1)The iTRAQ mass spectrometry is used to detect the whey protein and milk fat globule membrane protein between river-typed buffaloes and Holstein cows in mid-lactation.The differential expression profiles of whey protein and milk fat globule membrane protein were obtained.A total of 346 whey proteins were identified and 42 significant differentially expressed proteins were screened;370 milk fat globule membrane proteins were identified and 36 significantly differentially expressed proteins were screened.(2)Bioinformatics analysis of significantly differentially expressed proteins reveals that significantly differentially expressed whey proteins are predominantly enriched in GO terms that are defense responses,cytolysis,extracellular regions,complement activation,resistance to bacteria,stress response to organics,vitamin binding and transport,enzyme regulator activity and receptor metabolic process;The main enriched KEGG metabolic pathways are lysosomes and complement and coagulation cascades.Significantly differentially expressed MFGM proteins are mainly enriched in GO terms that are extracellular regions,sulfur compound binding,defense response to bacterium,protein-lipid complexes,lipoprotein particles,lipid biosynthesis process and ethanol biosynthesis process;No significant enrichment terms of the KEGG metabolic pathway.(3)STRING protein interaction network analysis are performed on the whey and fat globule membranes with differentially expressed proteins.It is found that serum albumin(ALB)forms a distinct node in the network,which is associated with various whey proteins and fat globule membrane proteins.Interactions indicate that it may have an important effect on the physiology of lactation.(4)The hierarchically clustered analysis of the significantly differently expressed proteins screened from the heat map shows that the three biological replicates are better,and the expression of differential proteins are consistent with the mass spectral results;Lactoferrin(LTF)and xanthine Xanthine dehydrogenase(XDH)are detected by western blot,and theirs expression pattern in buffalo and dairy protein samples are consistent with the mass spectrometry results.Through bioinformatics analysis,it was predicted that the whey differential proteins of buffalo milk and cow milk were related to disease resistance(KNG2,C3 and C7)and dairy storage time(LGMN,NAGA,PSAP,NPC2).The fat globule differential proteins are associated with cream biosynthesis(CYB5R3,APOA1,APOE).