Arabidopsis histidine kinase 2 (AHK2)

Arabidopsis histidine kinase 2 (AHK2) is a primary transmembrane receptor in Arabidopsis thaliana responsible for perceiving cytokinin, a vital plant hormone. It belongs to the two-component signaling system family and contains an extracellular CHASE domain for ligand binding, a cytoplasmic histidine kinase domain, and a receiver domain (UniProt Q9C5U1; Ueguchi et al., 2001). Upon binding cytokinins such as trans-zeatin, AHK2 initiates a multi-step phosphorelay cascade that activates downstream response regulators to modulate gene expression (Inoue et al., 2001). This signaling pathway is essential for regulating plant growth, including cell division, shoot apical meristem maintenance, and vascular development. AHK2 also plays a role in environmental adaptation, specifically acting as a negative regulator of drought and salt stress responses (Kang et al., 2012). While not a target for human medicine, AHK2 is a significant target in agricultural biotechnology for developing synthetic growth regulators and enhancing crop resilience. Agrochemicals like thidiazuron and 6-benzylaminopurine act as potent agonists of this receptor (Hothorn et al., 2011). Understanding AHK2's structural and functional properties allows for the precise manipulation of plant architecture and stress tolerance in agricultural settings.

Other names

AHK2HK2Cytokinin receptor 2Histidine kinase 2At2g17820

Ligand-induced histidine kinase autophosphorylation followed by a multi-step phosphorelay to response regulators.