Single nucleotide polymorphisms of GYS2 gene and its association with milk production traits of dairy cows.

Glycogen synthase 2 (GYS2) encodes liver glycogen synthase, a rate limiting enzyme in glycogen metabolism. Our preliminary work suggested that GYS2 was a candidate gene affecting milk production traits by analyzing the liver proteome of dairy cows. Herein, this research identified single nucleotide polymorphisms (SNPs) of GYS2, analyzed their genetic effects on traits of dairy cattle, and speculated the pathogenic mechanism through functional prediction of key mutation sites. Seven SNPs were found by resequencing and the association analysis showed that these SNPs were significantly associated with 305-day milk yield, fat yield, protein yield or fat percentage (p-value ≤ 0.0488). Six SNPs among them formed two haplotype blocks and they were associated with 305-day milk yield, fat yield, protein yield or fat percentage (p-value ≤ 0.0349). Furthermore, 5:g.88602007G > A and 5:g.88602026G > A were predicted to change the transcription factor binding sites (TFBSs), which might regulate the expression of GYS2. The missense mutation site, 5:g.88602535G > T, changed the secondary structure of mRNA and the secondary and tertiary structure of protein. In summary, the GYS2 was proved to have genetic effect on milk production traits, and its valuable seven SNPs, could provide more useful genetic information for molecular breeding of dairy cows.