The blood-brain barrier (BBB) is a unique cellular assembly found at the interface of the blood and the brain, composed mainly of tightly connected endothelial cells. The BBB forming endothelial cells are expected to have a distinct membrane protein expression profile and there is a great interest in finding BBB-specific membrane proteins. In addition, antibodies against these membrane proteins have a great potential as a means for targeted drug delivery to the brain.
The focus of our research is to identify BBB-targeting antibodies and apply them in the analysis of the BBB proteome. We are developing a method that couples the process of antibody generation with that of identification of the target membrane protein antigen. This is enabled by a powerful protein engineering platform called yeast surface display. We have developed a way to select membrane protein-binding antibodies, utilizing a human antibody library expressed on yeast cell surfaces. We then exploit a yeast immunoprecipitation (IP) method developed to provide a highly efficient method for characterizing membrane protein antigens. We have shown that we can determine protein sequence identification of the immunoprecipitated products using tandem mass spectrometry. The library screening and the yeast IP method are combined for highly efficient analysis of the BBB proteome.
Wang, X. X., Cho, Y. K., Shusta, E. V. Mining a yeast library for brain endothelial cell-binding antibodies. Nature Methods 4, 143-5 (2007)
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