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 plant cytokinin receptor Cre1, in the receptor-histidine kinase DhkA and the adenylyl cyclase Acg from the slime mold Dictyostelium discoideum, and in a variety of other receptor-like proteins from bacteria and eukaryotes. The domain is predicted to bind diverse low molecular weight ligands, such as the cytokinin-like adenine derivatives or peptides, and mediate signal transduction through the respective receptors.