Arabidopsis histidine kinase 4 (AHK4) (AHK4)

Arabidopsis histidine kinase 4 (AHK4), also known as Cytokinin response 1 (CRE1), is a vital transmembrane receptor in Arabidopsis thaliana that mediates the perception of cytokinins, a class of essential plant hormones [UniProt: Q9C5U0]. The receptor features an extracellular CHASE (Cyclases/Histidine kinases Associated Sensory Extracellular) domain that binds cytokinins like trans-zeatin and isopentenyladenine with high specificity [PubMed: 11449049]. Binding triggers a multi-step phosphorelay signaling cascade, where the histidine kinase domain autophosphorylates and transfers the phosphate group to histidine phosphotransfer proteins (AHPs), which then activate response regulators (ARRs) in the nucleus [PubMed: 11340201]. This pathway is fundamental for regulating plant growth processes, including cell division, vascular tissue differentiation, and root development [PubMed: 11449050]. While AHK4 is not a target for human medicine, it is a key target in agricultural science for developing plant growth regulators and herbicides [PubMed: 24501176]. Compounds such as thidiazuron act as potent agonists, while molecules like PI-55 serve as competitive inhibitors used to study cytokinin signaling and manipulate plant architecture [PubMed: 22135445].

Other names

Cytokinin response 1CRE1Wooden legWOLCytokinin receptor 1CYT1

Agonist-induced autophosphorylation and multi-step phosphorelay