Cluster of Excellence, University of Freiburg

Generation and composition of functional nanodomains on Lymphocytes

Prof. Dr. Michael Reth (CIBSS-AI), Institute of Biology III – Molecular Immunology (Faculty of Biology), University of Freiburg

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This project is based on our recent super-resolution studies showing, that membrane proteins are highly organized at nanometer distances inside functional membrane compartments called protein islands. Specifically we found that the B cell antigen receptors (BCR) of class IgM and IgD are confined together with other proteins in separated class-specific protein islands and the same is true for inhibitory receptors such as CD22. Where and how these protein islands are formed and the sorting code of its components is currently unknown. We think that this organization is established during the vesicular transport from the ER through the Golgi to the plasma membrane and we want to identify the molecular code for this sorting process.

To follow the intracellular transport of the IgM and IgD class BCR in living B cells we expressed SNAP-tagged mIgM and HALO-tagged mIgD in BCR-deficient Ramos human B cells and showed that these molecules can be specifically labelled with different colours. We also have developed a new highly efficient CRISPR/Cas 9 protocol (60-80% KO) based on the direct delivery of pre-assembled Cas 9 proteins into B cells. With this method we want to identify the genes whose products are required for the establishment and maintenance of different protein islands.