Arabidopsis histidine kinase 3 (AHK3) (AHK3)

Arabidopsis histidine kinase 3 (AHK3) is a primary transmembrane receptor in the model plant Arabidopsis thaliana that perceives cytokinins, a group of hormones vital for plant growth and development [1, 2]. It consists of an extracellular CHASE domain for ligand binding, a cytoplasmic histidine kinase domain, and a receiver domain that facilitates a multi-step phosphorelay signaling cascade [1, 4]. AHK3 plays a predominant role in regulating the maintenance of the shoot apical meristem and is the principal receptor responsible for delaying leaf senescence [2, 3]. Beyond development, AHK3 is involved in the plant's response to environmental stressors, including drought, salinity, and cold, by modulating the expression of type-A Arabidopsis response regulators [3, 4]. While not a target for human clinical therapy, AHK3 is a major focus in agricultural biotechnology for developing crops with improved yield and enhanced tolerance to climate-related stress [2, 4]. The receptor interacts with various natural and synthetic cytokinins, such as trans-zeatin and thidiazuron, which act as agonists to trigger downstream signaling [1, 2].

Other names

Histidine kinase 3CRE2Cytokinin Response 2WOL2Wooden Leg 2AT1G27320

Cytokinin binding to the extracellular CHASE domain induces a conformational change that activates the intracellular histidine kinase domain, leading to autophosphorylation and a subsequent multi-step phosphorelay to Arabidopsis response regulators (ARRs).