Differential expression of liver proteins in Chianina and Holstein young bulls

The purpose of this work was to produce and compare liver proteomic maps of cattle breeds that have been selected for different purposes: dairy (Holstein) and beef (Chianina). Liver was chosen because it displays functions of synthesis, homeostasis, excretion, and defense. Two dimensional electrophoresis analyses were performed on bovine livers collected from 4 individuals of each breed to evaluate differential protein expression. We found 9 spots differing in photodensity by >or=2-fold between the 2 breeds. Spots were analyzed through matrix-assisted laser desorption ionization mass spectrometry-time of flight (MALDI-TOF MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS). A search against protein sequences in the National Center for Biotechnology Information databases indicated that the differentially expressed proteins correspond to liver-specific enzymes, with a major role in the metabolism of fatty acids, carbohydrates, AA, and the urea cycle.