Abstract: To understand the molecular mechanism at protein level and find the crucial proteins which correlate with lactating, two-dimensional electrophoresis was applied to separate subcellular proteins of healthy dairy cow mammary gland epithelial cells and methionine-supplemented dairy cow mammary gland epithelial cells cultured in vitro. The Image Master 2-DE software was used to characterize different proteins. By matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) and database searching, proteins were identified. The 2-DE results were verified on the mRNA level by real time quantitative PCR. Eight differentially-expressed proteins from MS analysis were of up-regulated expression. The differentially displayed proteins between control and methionine-supplemented dairy cow mammary gland epithelial cells are useful for lactating mechanism research.

Key words: methionine; dairy cow; mammary gland epithelial cell; two-dimensional electrophoresis; proteomics