The chemotaxis system of Escherichia coli is sensitive to small relative changes in ambient chemoattractant concentrations over a broad range. Interactions among receptors are crucial to this sensitivity, as is precise adaptation, the return of chemoreceptor activity to prestimulus levels in a constant chemoeffector environment through methylation and demethylation of receptors. Signal integration and cooperativity have been attributed to strongly coupled, mixed teams of receptors, but receptors become individually methylated according to their ligand occupancy states. Here, we present a model of dynamic signaling teams that reconciles strong coupling among receptors with receptor-specific methylation. Receptor trimers of dimers couple to form a honeycomb lattice, consistent with cryo-electron microscopy (cryoEM) tomography, within which the boundaries of signaling teams change rapidly. Our model helps explain the inferred increase in signaling team size with receptor modification, and indicates that active trimers couple more strongly than inactive trimers.adaptation | modeling | receptor clustering A daptation to persistent stimuli is important in maintaining a broad range of response-sensitivity in numerous sensory systems, including visual (1), olfactory (2), and auditory (3). The best understood example of such adaptation is the Escherichia coli chemotaxis system (Fig. 1A), in which receptor signaling adapts precisely to persistent chemoeffector concentrations. Adaptation is implemented by the methylation and demethylation of transmembrane receptors through an integral-feedback control mechanism (4, 5). Different receptor types bind specific ligands, but signal cooperatively in mixed teams (6, 7). One feature of this system that has remained mysterious is that, at short times, adaptation leads to similar modification of all receptors, but at longer times, modification is receptor-type specific, affecting primarily the receptors stimulated by ligand (8). Here, we present a model of dynamic-signaling teams that reconciles receptor cooperativity with receptor-specific methylation.Receptors direct cell movement by biasing the switching between tumbling and straight-swimming states, producing a biased random walk up gradients of chemoattractants or down gradients of chemorepellents. Of the five receptor types in E. coli, the highest abundance are Tar (aspartate binding) and Tsr (serine binding). Receptors form homodimers that can each bind one molecule of ligand. Homodimers, which we will refer to as receptors, in turn form mixed trimers of dimers, and associate with the linker protein CheW and the histidine kinase CheA (9). Receptor signaling activates CheA autophosphorylation, and the phosphoryl group is transferred to the response regulator CheY (or to the methylesterase CheB). Phosphorylated CheY diffuses and binds to the flagellar motors, causing tumbling. CheY is dephosphorylated by the phosphatase CheZ. Receptor trimers of dimers form the basic signaling units, with single receptors unable to activate Che...