Chemotaxis Receptor A (CheA) is involved in the cytoplasmic phosphorylation cascade that couples changes in bacterial swimming behaviour to the external concentrations of attractants and repellents. CheA catalyses the trans-phosphorylation of CheY to generate intracellular signals between the membrane-spanning chemoreceptors and the flagellar motor. The CheA homodimer responds to asymmetric activation. Although there are two ATP-binding sites, one per CheA dimer, only a single binding domain at any given time can participate in catalysis. An aspartate reside of the chemoreceptor CheY is specifically phosphorylated as part of the chemotaxis cascade.
