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Our group is interested in the mechanisms and molecular logic that govern the molecular interactions of proteins. The focus is on proteins with a known functional impact on adaptive immunity or neuronal function. NMR spectroscopy is used to question the structural properties of molecules while mass spectrometric studies report on the compositional dynamics of proteomes when cells are challenged by intracellular or extracellular cues. A particular focus is on proteins of the human leukocyte antigen (HLA) family that present processed protein antigens to T cells. Here certain determinants of antigen processing and presentation are interrogated in the context of autoimmunity or viral infections. Activation of T cells by antigenic stimuli is followed by our group for proteins that modulate critical intracellular pathways. This ranges from crucial factors of T cell motility (ADAP) to modulators of membrane anchorage (palmitoyl transferases) and proteins that impact mRNA splicing (CD2BP2). In the case of proteins of the nervous system we are interested in factors that enable fast exocytosis or that play a role in the synaptic vesicle cycle (Syntaxin-1B, intersectin). In all cases, collaborations with groups interested in the biology of these molecules help to draw a more complete picture about their specific role in the cell and/or in the context of disease.

Projects in the AG Freund

1. Antigen presentation by Major Human Histocompatibility complex class II (MHCII) proteins

Cell-mediated adaptive immunity by T cells critically depends on antigen presentation by MHCII proteins. We investigate this process at the molecular and cellular level and thereby frame the implications it has for wanted and unwanted immune reactions.

2. Scaffolding proteins at the membrane

Inducible recruitment of proteins to the plasma membrane constitutes a pivotal initial step in many signal transduction processes. We interrogate proteins important for neuronal or
T cell function with regard to their intramolecular and intermolecular interactions and we profile the post-translational modifications that enable their membrane association by protein biochemical, biophysical and cell biological methods.

3. Interactions between Proline-rich Sequences and interacting domains in the Spliceosome

We are studying the proline-rich-sequence-binding proteins CD2BP2 and FBP21, their spliceosomal interaction partners and their function in splicing and alternative splicing. In addition, we are trying to modulate the interaction with their respective binding partners through the design of (multivalent) inhibitors.