CheX is very closely related to the CheC chemotaxis phosphatase, but it dimerises in a different way, via a continuous beta sheet between the subunits. CheC and CheX both dephosphorylate CheY, although CheC requires binding of CheD to achieve the activity of CheX. The ability of bacteria to modulate their swimming behaviour in the presence of external chemicals (nutrients and repellents) is one of the most rudimentary behavioural responses known, but the the individual components are very sensitively tuned [1].

1: Structure and function of an unusual family of protein phosphatases: the bacterial chemotaxis proteins CheC and CheX. Park SY, Chao X, Gonzalez-Bonet G, Beel BD, Bilwes AM, Crane BR; Mol Cell. 2004;16:563-574. PMID:15546616