It is estimated that between 30 and 40 percent of all cellular proteins reside in the non-aqueous environment of lipid membranes where they perform crucial metabolic functions and regulate the transfer of information and material into and out of the cell. Because membrane proteins govern such processes as nutrient uptake, drug efflux, respiration, sensory physiology, endocrine function, immunity and neuronal communication, they are central players in numerous disease states and host-pathogen interactions. To understand and modulate any of these processes, a thorough understanding of the activities of the respective membrane protein components - at the molecular level - is an absolute requirement.
The location of these proteins in hydrophobic membranes presents extreme difficulties for their isolation and characterisation, with the result that knowledge of membrane proteins lags far behind that of soluble proteins. The lack of detailed structural and functional information on these essential molecular machines is one of the most pressing problems of modern biology. The four Departments at the Max Planck Institute of Biophysics employ a variety of complementary techniques to resolve the details of membrane protein biology. The contexts explored in individual projects range from the organismal to the atomic, with the goal of integrating findings at all levels to generate a complete picture of the processes under study.
Since 1987 the Department of Molecular Membrane Biology uses X-ray crystallography as its primary tool. Under the direction of Hartmut Michel (Nobel Prize in Chemistry of 1988 for the first structure determination of a membrane protein), the Department has illuminated the structure and mechanisms of three of the four electron transfer complexes of the respiratory chain and is actively pursuing structures of secondary transporters and G-protein coupled receptors (GPCRs). The Department of Structural Biology established in 1996 and headed by Werner Kühlbrandt, uses electron microscopy to analyze 2D crystals as well as large complexes by single-particle methods or electron tomography to determine their structures and mechanisms. Long-standing project areas include structural work on transport proteins such as ATPases, symporters, antiporters and translocon complexes, and on plant photosynthetic complexes. The Department of Theoretical Biophysics , founded by Gerhard Hummer in 2013, studies the structure, stability, dynamics, and function of biomolecules and their complexes using theory and simulation. Biomolecular systems are investigated with the tools of statistical physics and quantum chemistry. Molecular dynamics and Monte Carlo simulations provide a detailed, atomistic description of key biomolecular processes, from biological energy conversion to cellular transport and signalling. The Department of Molecular Sociology was newly established in 2020 under the leadership of Martin Beck. The main topic is the integrated structural analysis of the nuclear pore complex in situ and the structural analysis of peripheral subcomplexes and nuclear pore complex dynamics. Also the phylogenetic diversity of nuclear pore complex architecture will be explored. The emeritus group of the former Department of Biophysical Chemistry, founded in 1993 and directed by Ernst Bamberg, applies high precision electrophysiological and spectroscopic methods to directly probe the mechanisms of action of ion pumps and transporters directly in lipid membranes. Transport cycle information is obtained from measurements on living cells as well as in vitro using solid supported bilayer techniques.