Basic molecular mechanisms of cell surface receptors that mediate transmembrane signals can be elucidated by integrating information from multiple interdisciplinary approaches. Our studies focus on the receptor (FceRI) for immunoglobulin E (IgE) that plays a central role in the allergic response and serves as a model for other types of immune receptors. Binding and cross-linking of IgE-FceRI complexes by antigen initiates signal transduction resulting in cell activation and release of chemical mediators.
We measure kinetics and thermodynamics of binding and cross-linking between cell-bound IgE and structurally defined ligands with fluorescence methods and analyze with realistic theoretical models to determine features that are critical for signaling. We employ quantitative fluorescence microscopy, including confocal imaging and total internal reflection fluorescence (TIRF) microscopy, to monitor changes in the distribution and dynamics of the receptor and signaling components (and genetically engineered analogs) that accompany receptor cross-linking and cellular activation. We also utilize super resolution fluorescence microscopy to provide a molecular scale view of structural assemblies and their dynamics on the cell surface.
Using biochemical and biophysical approaches we found that IgE receptor-mediated signaling involves plasma membrane domains that enable regulation and targeting of the signaling components. Our ongoing collaborative studies apply a range of powerful analytical methods to investigate the composition, structure and dynamics of the participating membrane components. Molecular and supramolecular structures within cells underlie stimulated cellular activities such as phosphorylation, Ca2+ mobilization, membrane trafficking, and exocytosis. Measurement of physico-chemical changes in conjunction with biological processes drives our ongoing understanding of these complicated cellular responses. Together with these other approaches, we are helping to develop nanotechnology to probe biological systems on subcellular and molecular scales.