Our group is working on two major topics: biogenesis and characterization of membrane proteins and a detailed understanding of the targeting/insertion machinery of the signal recognition particle.



A wide range of fundamental biological processes such as energy and information transport across biological membranes is mediated by membrane proteins. However, compared to their importance our knowledge about the three-dimensional structures of G protein coupled receptors (GPCRs), channels of transporters is very limited. Structural information will significantly increase our understanding of the molecular mechanisms of membrane transport and signal transduction. Unfortunately, most of these proteins are present in their natural membranes only in minute amounts and therefore, the overproduction in suitable host systems is the key step for further studies. Current projects with membrane proteins include a number of transport proteins from bacteria and yeast and G-protein coupled receptors. Our strategies include biochemical and biophysical methods and the use of monoclonal antibodies for co-crystallization. For expression of GPCRs we have developed a novel expression system in the photoreceptor cells of eye of Drosophila melanogaster.

All membrane proteins have to be targeted to and inserted into the correct membrane. The signal recognition particle (SRP) is a universally conserved system for the transport of secretory and membrane proteins to the ER or the plasma membrane. SRP is a ribonucleoprotein comprised of an RNA molecule (7S RNA in mammals, 4.5 S RNA in E. coli) and a protein part (six protein subunits ranging from 9 to 72 kDa in mammals, one protein in bacteria). Current projects with SRP include the assembly of larger complexes of SRP and its receptor (including Archaebacteria and the plant chloroplast) for structural and biochemical characterization.

Methods: X-ray crystallography, biochemistry, biophysics and molecular biology.