Chemotaxis protein interaction network. The spoke model was used to derive binary interactions from the copurification data. Only proteins discussed in the text are shown. The complete network is depicted in Additional file 6. The prefixes “Che” and “Htr” were omitted from the protein labels. The core signaling proteins CheA, CheW1 and CheY are highlighted by red shading. The weak binding of CheW2 to the core signaling complexes (see text) is indicated by red and white stripes. The gray areas delineate different groups of Htrs that can be distinguished by their interactions with CheA, CheR, CheW1, CheW2 and CheY (see text). For clarity, interactions identified with these baits are shown in different colors.