Phosphoproteomics Preliminarily Revealed the Differential Phosphorylation Sites and Their Functional Significance in the Longissimus Dorsi Muscle of Kazakh and Xinjiang Brown Cattle.

As the life science technology developed fast, various proteomics were applicable to human medical research and livestock production. To further study the differences in muscle production and development between Kazakh cattle and Xinjiang brown cattle, we performed phosphoproteomic analysis of the longissimus dorsi muscle tissue of Xinjiang brown cattle and Kazakh cattle. We found that there were 22 disparately expressed proteins, of which 6 were upregulated and 16 were downregulated. There were 28 differentially phosphorylated sites, including 6 sites with increased phosphorylation levels and 22 sites with decreased phosphorylation levels. In addition, PRM revealed that the levels of PDLIM3, PPP1R3A, MYPN, and IGFN1 were significantly increased in Xinjiang brown cattle, and these results were similar to those of the phosphoproteomic analysis. Based on the species conservation, we knocked down the expression of RAB12 in C2C12 cells. We found that after RAB12 was knocked down, the protein levels of the myogenic differentiation marker MYOG were significantly increased, and the immunofluorescence intensity of MYHC was also increased.