Proteins of rat serum: I. Establishing a reference two-dimensional electrophoresis map by immunodetection and microbore high performance liquid chromatography-electrospray mass spectrometry

In the present investigation, we have identified 56 major spots, or spot rows, corresponding to 22 proteins, in the 2‐DE pattern of adult male rats. This was done mainly by applying two complementary techniques, namely immunoblotting and high performance liquid chromatography‐mass spectrometry (HPLC‐MS) peptide mapping. Glycoproteins were characterized by affinity blotting with six lectins. We have also detailed how rat serum differs from human serum in two main respects: (i) relative abundance of individual proteins, which amounts in some cases to a complete absence in either sample, and (ii) varying molecular parameters for homologous proteins. It was thus possible to establish a first‐generation reference map of rat serum proteins, which can be accessed through http://weber.u.washington.edu/∼ruedilab/aebersold.html. We hope the present database will be a useful reference for the evaluation of changes in serum protein distribution in the course of pharmacological and toxicological studies. The recognition of species‐specific proteins appears of special relevance in this respect.