The CHASE domain: a predicted ligand-binding module in plant cytokinin receptors and other eukaryotic and bacterial receptors

A novel, 200-230 amino acid extracellular domain was identified in the plan t cytokinin receptor Cre1, in the receptor-histidine kinase DhkA and the ad enylyl cyclase Acg from the slime mold Dictyostelium discoideum, and in a v ariety of other receptor-like proteins from bacteria and eukaryotes. The do main is predicted to bind diverse low molecular weight ligands, such as the cytokinin-like adenine derivatives or peptides, and mediate signal transdu ction through the respective receptors.