We study signal processing in cells. We want to understand how sensory stimuli are detected by cells and converted into a cellular response. Signal transduction in cells is a fascinating topic that is studied by many scientists throughout the world. The in-depth understanding of this complex process requires the use of biological, chemical, and physical techniques. Therefore, biologists, chemists, and physicists work closely together in the department.
Sensory cells convert a stimulus into an electrical signal. In the retina, photoreceptor cells detect light and transduce this information into an electrical signal through a series of biochemical reactions. This signal is then relayed to visual centers in the brain. In the nose, olfactory cells generate an electrical signal in response to an odor. This signal encodes the quality and strength of the olfactory stimulus. Our research aims to reveal the molecular mechanisms underlying sensory transduction. To this end, we study the structure, function, and interaction of proteins involved in these processes. In particular, we study ion channels that are involved in the generation of electrical signals. These ion channels include the cyclic nucleotide-gated (CNG) channels and the hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels, which are also known as pacemaker channels. Moreover, we study the supramolecular organization of receptors and ion channels by cryo-electron tomography.
The success of fertilization depends on the ability of motile sperm to locate the egg. Sperm cells swim with the help of a flagellum and their swimming behavior is determined by chemical attractants that are released by the egg. What are these attractants and how do sperm detect these attractants? The detection is based on mechanisms similar to those involved in the detection of odors and light by olfactory neurons and photoreceptors, respectively. Moreover, similar signaling molecules are involved. We study the signaling pathways underlying chemosensation in sperm of sea urchins and humans. In particular, we are interested in the receptors, cellular messengers and ion channels that endow sperm with such exquisite sensitivity.
We develop optical switches that are used in the photonic control of receptors and ion channels. These compounds are, in fact, "Trojan horses" that are "smuggled" into the cell. On exposure to light, the compounds release the signaling molecules. With the help of these Trojan horses, cellular signal pathways can be resolved with great precision, both temporally and spatially. The so-calles caged compounds - together with fast kinetic methods such as quenched-flow and stopped-flow - are used to track conformational changes of proteins in space and time with submillisecond and Ångstrom resolution.