Involved in the transmission of sensory signals from the chemoreceptors to the flagellar motors. It physically bridges CheA to the MCPs (methyl-accepting chemotaxis proteins) to allow regulated phosphotransfer to CheY and CheB. An in vitro complex of CheW/CheA(L)/CheA(S) in a 1:1:1 ratio increases the autophosphorylation of CheA and is required for the binding of CheY, the phosphorylation substrate. This complex accounts for 10% of the total number of molecules.