OST1
Protein DomainOST1 is an Arabidopsis thaliana protein kinase domain identified by positional cloning as an abscisic acid (ABA)-activated kinase expressed in stomatal guard cells and vascular tissue. Genetic and physiological evidence places OST1 as a regulator of stomatal movement, acting upstream of reactive oxygen species production and interacting genetically with HT1 during red light- and CO2-responsive stomatal responses.