Case Study:
Bcl-2 Associated Athanogene 3 (BAG3)

This is an example on how to use the same solubilization methodology to maintain protein-protein interaction and therefore, learn about the partners of a given protein. We could identify the membrane protein partner of BAG3 (Bcl-2 associated athanogene 3). This protein is released by pancreatic ductal adenocarcinoma (PDAC) cells and activates macrophages through a specific unknown receptor.

BAG3 is a soluble protein that is known to be present very often on the surface of the macrophage (fluorescence). The idea is to apply our solubilization methodologies to maintain protein-protein interactions and after co-purification, mass spectrometry could identify the protein partner.

One of the partners IFITM2 (Interferon-induced transmembrane protein 2) has been identified in the experiment but not in the negative control. This was confirmed by other experiments as complementary Co-IP approach of IFITM2 (described here) and by RNAi approach.

We have conducted very similar work for other projects. This is a powerful tool to understand the mechanism of action and identify protein partner in a native environment.

References

Nature communications

BAG3 promotes pancreatic ductal adenocarcinoma growth by activating stromal macrophages

   Rosati A et al. 2015