Expression and Characterization of a Lysine Rich Protein in Cow Milk

The lysine is considered as the most important essential amino acid, because it is the most limiting in the cereals grains. In this study, a lysine-rich (LR) gene, and the expression vector pcDNA3.1-LR and pBC1-LR were constructed. The LR was expressed in 293T cells driven by the vector pcDNA3.1-LR and checked by RT-PCR and WB. The mammary gland tissue-specific expression vector carrying the LR was injected directly into the lactating mammary glands of cows and the milk samples were checked by a complete amino acid analysis. The results showed that the LR protein was expressed successfully in cells and in cow milk; the expression of LR lasted for 6 d, and the lysine level of the injection group was significantly higher than that of negative controls (p Lass Than 0.05). This study provide a better understanding of how mammary gland expression systems increase the lysine content of milk that can be applied to transgenic dairy cow.