乳蛋白是牛奶营养品质的重要物质基础，κ-酪蛋白作为主要的乳蛋白在稳定酪蛋白结构和乳品加工中具有重要作用。氨基酸不仅是乳蛋白合成的底物，也可以调节乳蛋白的合成，但氨基酸如何影响κ-酪蛋白合成的调控机制尚不明确。只有弄清楚其影响机理，才能提出科学合理利用氨基酸的营养调控途径。传统营养学手段研究必需氨基酸对乳蛋白的影响仅能做表观描述和假设分析，无法从深层次解析必需氨基酸调节乳蛋白合成的机制。本项目在确定可显著提高κ-酪蛋白合成必需氨基酸的基础上，拟采用转录组和蛋白质组学方法，研究必需氨基酸在转录和蛋白水平对牛乳κ-酪蛋白合成的影响，寻找差异基因和蛋白，构建关键基因和蛋白网络，从而深入解析κ-酪蛋白合成的信号通路。本项目的最终目标是阐明必需氨基酸调节牛乳κ-酪蛋白的合成机制，为通过分子营养调控技术提高κ-酪蛋白的合成提供科学依据。

Milk protein is one of the major nutritional components associated with milk quality，while κ-casein plays a critical role in stabilization of casein structure and milk manufacture properties. Amino acids not only serve as precursors for protein synthesis, but also act to regulate rates of protein synthesis. However, it is not clear how amino acids regulate the κ-casein synthesis. Clarification of mechanism involved is helpful to develop the nutrition strategies for efficient utilization of amino acids. Conventional methods for study of the effect of essential amino acids on milk protein can only describe apparent problems and do some speculative analysis, but they are difficult to reveal regulatory mechanisms related to milk protein synthesis. In the proposed study, based on determination of essential amino acids that could increase κ-casein synthesis, the integrated transcriptomics and proteomics approach will be employed to analyze the effect of essential amino acids on milk κ-casein synthesis at both transcriptional and protein levels. We will screen significantly differential genes and proteins to characterize the network of key genes and protein and then signaling pathway related with κ-casein synthesis, and provide the basic knowledge for better understanding of the synthesis pathway of κ-casein in the bovine mammary glands. The final aim of this proposal is to reveal the regulatory mechanism with which essential amino acids affect κ-casein synthesis, and to provide deep insight for improving κ-casein synthesis through nutritional strategies in dairy cow.