A5034531020- Lipid Membrane Structure and Behavior
- Cellular transport and secretion
- Cell Adhesion Molecules Research
- Platelet Disorders and Treatments
- Erythrocyte Function and Pathophysiology
- Immunotherapy and Immune Responses
- Protein Structure and Dynamics
- RNA and protein synthesis mechanisms
- Calcium signaling and nucleotide metabolism
- HER2/EGFR in Cancer Research
- Endoplasmic Reticulum Stress and Disease
- Biochemical and Structural Characterization
- Retinal Development and Disorders
- T-cell and B-cell Immunology
- Caveolin-1 and cellular processes
- Immune Cell Function and Interaction
- Monoclonal and Polyclonal Antibodies Research
- Receptor Mechanisms and Signaling
- Advanced Fluorescence Microscopy Techniques
- Alzheimer's disease research and treatments
- Glycosylation and Glycoproteins Research
- Soil Mechanics and Vehicle Dynamics
- Hydraulic and Pneumatic Systems
- Lung Cancer Treatments and Mutations
- Immune Response and Inflammation
University of Bonn
2015-2025
Life & Brain (Germany)
2016-2018
Polis University
2016
Max Planck Institute for Biophysical Chemistry
2000-2011
Max Planck Society
1999-2009
Howard Hughes Medical Institute
2002
Yale University
2002
Max Planck Institute for Medical Research
1997-1999
Most plasmalemmal proteins organize in submicrometer-sized clusters whose architecture and dynamics are still enigmatic. With syntaxin 1 as an example, we applied a combination of far-field optical nanoscopy, biochemistry, fluorescence recovery after photobleaching (FRAP) analysis, simulations to show that clustering can be explained by self-organization based on simple physical principles. On average, the exhibit diameter 50 60 nanometers contain 75 densely crowded syntaxins dynamically...
During exocytosis, certain phospholipids may act as regulators of secretion. Here, we used several independent approaches to perturb the phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] level in bovine chromaffin cells investigate how changes plasmalemmal PI(4,5)P2 affect Membrane levels were estimated by analyzing images lawns plasma membranes labeled with fluorescent probes specific for PI(4,5)P2. The signal was enriched submicrometer-sized clusters. In parallel patch-clamp experiments on...
During exocytosis, secretory granules fuse with the plasma membrane and discharge their content into extracellular space. The exocytosed is then reinternalized in a coordinated fashion. A role of clathrin-coated vesicles this process well established, whereas involvement direct retrieval mechanism (often called kiss run) still debated. Here we report that significant population docked neuroendocrine cell line PC12 fuses membrane, takes up fluid-phase markers, retrieved at same position....
Most proteins have uneven distributions in the plasma membrane. Broadly speaking, this may be caused by mechanisms specific to each protein, or a consequence of general pattern that affects distribution all membrane proteins. The latter hypothesis has been difficult test past. Here, we introduce several approaches based on click chemistry, through which study living cells, as well sheets. We found form multi-protein assemblies are long lived (minutes), and protein diffusion is restricted....
Membrane fusion in the secretory pathway is mediated by soluble N -ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins. Different steps are thought to be effected independent sets of SNAREs, but it unclear whether specificity determined an intrinsic SNARE pairing or upstream factors. Using a newly developed microscopy-based assay, we have investigated homotypic early endosomal fusion. We show that endosomes contain multiple including, addition putative those involved...
Tomosyn is a 130-kDa syntaxin-binding protein that contains large N-terminal domain with WD40 repeats and C-terminal homologous to R-SNAREs. Here we show tomosyn forms genuine SNARE core complexes the SNAREs syntaxin 1 SNAP-25. In vitro studies recombinant proteins revealed complex formation proceeds from unstructured monomers stable four-helical bundle. The assembled displayed features typical for complexes, including profound hysteresis upon unfolding-refolding transitions. No were formed...
Munc18–1, a protein essential for regulated exocytosis in neurons and neuroendocrine cells, belongs to the family of Sec1/Munc18-like (SM) proteins. In vitro, Munc18–1 forms tight complex with SNARE syntaxin 1, which is stabilized closed conformation. Since unable interact its partner SNAREs SNAP-25 synaptobrevin as required membrane fusion, it has hitherto not been possible reconcile binding 1 biological function. We now show that intact exocytosis-competent lawns plasma membrane, allows...
Myelin basic protein (MBP) is an essential structural component of CNS myelin. The electrostatic association this positively charged with myelin-forming membranes a crucial step in myelination, but the mechanism that regulates myelin membrane targeting not known. Here, we demonstrate phosphatidylinositol 4,5-bisphosphate (PIP2) important for stable MBP cellular membranes. In oligodendrocytes, overexpression synaptojanin 1-derived phosphoinositide 5-phosphatase, which selectively hydrolyzes...
During neuronal exocytosis, the vesicle-bound soluble NSF attachment protein (SNAP) receptor (SNARE) synaptobrevin 2 forms complexes with plasma membrane–bound SNAREs syntaxin 1A and SNAP25 to initiate fusion reaction. However, it is not known whether in native membrane are constitutively active or they unable enter SNARE unless activated before fusion. Here we used binding of labeled recombinant inside-out carrier supported sheets PC12 cells probe for activity endogenous SNAREs. Binding was...
We have developed a cell-free system for regulated exocytosis in the PC12 neuroendocrine cell line. Secretory vesicles were preloaded with acridine orange intact cells, and cells sonicated to produce flat, carrier-supported plasma membrane patches attached vesicles. Exocytosis resulted release of which was visible as disappearance labeled and, under optimal conditions, produced light flashes by fluorescence dequenching. vitro requires cytosol Ca2+ at concentrations micromolar range, is...
Abstract Biochemical approaches revealed that tetraspanins are multi-regulatory proteins forming a web, where they act in tetraspanin-enriched-microdomains (TEMs). A microscopic criterion differentiating between web and TEMs is lacking. Using super-resolution microcopy, we identify co-assemblies the CD9 CD81 CD151 CD81. assemblies contain as well CD9/CD81-interaction partner EWI-2. Moreover, clusters proximal to of CD81-interaction CD44 CD81-/EWI-2-interacting ezrin–radixin–moesin proteins....
The essential membrane fusion apparatus in mammalian cells, the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, consists of four alpha-helices formed by three proteins: SNAP-25, syntaxin 1, and synaptobrevin 2. SNAP-25 contributes two helices to complex is targeted plasma palmitoylation cysteines linker region. It alternatively spliced into forms, SNAP-25a SNAP-25b, differing nine amino acids substitutions. When expressed chromaffin cells from null...
In the present study, we have used wild-type and palmitoylation-deficient mouse 5-hydroxytryptamine(1A) receptor (5-HT1A) receptors fused to yellow fluorescent protein- cyan protein (CFP)-tagged alpha(i3) subunit of heterotrimeric G-protein study spatiotemporal distribution 5-HT1A-mediated signaling in living cells. We also addressed question on molecular mechanisms by which palmitoylation may regulate communication between G(i)-proteins. Our data demonstrate that activation 5-HT1A caused a...