Chemotaxis is a common biological behavior that allows living organisms to move towards chemical stimuli and it has served as a model for the study of cellular sensory signal transduction and motile behavior. Escherichia coli's basic chemotaxis machinery is the most well-characterized signal transduction system, and it serves as a great tool for studying molecular processes involved in chemotaxis. E. coli cells' sensory machinery is a highly organized array of hundreds of basic core signaling units comprised of three essential components: transmembrane chemoreceptors, histidine kinase, and adaptor protein. Such organization allows cells to amplify and integrate many different signals to find optimal growth circumstances. It is necessary to characterize the precise interactions between the core signaling components in the array and in the native cellular context to understand the molecular processes of chemosensory array formation, activation, and high cooperativity. The most critical part of this project is to reveal the sequential conformational changes during signaling. To do so, the time-resolved method will be developed and combined with cryoelectron tomography for in situ structural analysis. The project aims for a molecular movie of chemotaxis signaling events at nearatomic resolution.