IBI-1 conducts basic research in the field of molecular neurobiology and cellular signal processing.

Chemical and physical stimuli trigger a specific response in many biological cells. The biochemical reactions from recognizing the stimulus up to the physiological response are also referred to as signal transduction, because the information of the stimulus is translated in a multistage process. The Institute especially investigates the stimulation of visual cells of the mammalian retina and their adaptation, the mechanism of signal transduction in olfactory cells of the olfactory epithelium, taste cells of the lingual epithelium and in sperm.

Many steps of neuronal signal processing are bound to cellular membranes. The stimulus-specific receptors of a cell are integral membrane proteins, and the cellular response in many cases consists in a modification of the electrical conductivity of the cell membrane mediated by ion channels. A priority topic of the Institute is the characterization of different ion channels by biochemical, molecular biological and biophysical methods.

The mechanisms of signal transduction and neuronal stimulation are based in many cases on reciprocal recognition and the interaction between proteins and the formation of macromolecular signal complexes. The long-term aim is to understand the individual steps of signal transduction and ion translocation in single molecules as well as the structure and dynamics of the signal complexes.

Undisturbed information processing is vital for all biological systems. Many diseases are based on defects in the processing of signals inside cells or between cells and thus on a disturbance of their specific function. IBI-1 therefore investigates the molecular causes for different degenerative and functional diseases of the retina. In the long term, the findings may also serve to indicate new approaches to the technical solution of problems of information processing using biological devices ("biosensors") or functional principles ("molecular recognition").

The aim of work at the department of Biological Structure Research (IBI-2) is to understand the molecular mechanism of proteins on the basis of their structure and dynamics. A main focus is on membrane proteins, which transport substances and signals through membranes. Bacteriorhodopsin, a light-driven proton pump, examplifies these efforts. High-resolution crystal structures have not only been determined for the ground state, but also for some important intermediate states. Time-resolved infrared spectroscopy makes the pathway of the proton through bacteriorhodopsin visible from the changes of the vibration bands of groups capable of being protonated. The analysis of equilibrium fluctuations by quasi-elastic neutron scattering shows the significance of diffusive motions, which enable the conformational changes important for the functions. It has been found that bacteriorhodopsin is a model system for seven a-helical active ion pumps and also for many receptors of this protein family. Apart from many other projects, IBI-2 will in future investigate ion channels, especially in cooperation with IBI-1, which in many systems cause the conversion of a sensory cascade into an electrical signal. The main methods of investigation are currently crystal structure analysis, multidimensional NMR and time-resolved infrared and Raman spectroscopy.