More than two-thirds of all described drug targets are membrane proteins, but structure analysis and protein production for these hydrophobic proteins is inherently challenging. Consequently, investigations of their mechanisms of function and drug interactions are often only derived from purified truncated parts of these proteins, taken out of the native biological context. Without the effects of the surrounding membrane components, conclusions on drug mechanisms are incomplete. Recent advances of in situ structure determination techniques, i.e. analysis directly within the cellular environment, have the power to overcome the limitations of classical reconstituted approaches. Complementary, we have developed a system that facilitates structural analysis of membrane protein targets and has large potential for the production of native membrane proteins - an essential prerequisite for studying membrane protein function and drug interactions.
Within the scope of our proposal, we have further developed our system and transferred it into a pharmaceutically-relevant human cell system. Furthermore, we achieved proof-of-concept and assessed our system with clinically-relevant membrane proteins for its suitability for membrane protein production, as well as suitability to solve 3D structures of membrane protein complexes by cryo-electron tomography (cryo-ET) directly in cells. Our approach can have a transformative impact on how membrane protein interactions can be studied, and could in the future be exploited for drug development by the pharmaceutical industry.
