Serine/Threonine-Protein Kinase SRK2E (SRK2E) Arabidopsis Thaliana Recombinant Protein

Encodes calcium-independent ABA-activated protein kinase, a member of SNF1-related protein kinases (SnRK2) whose activity is activated by ionic (salt) and non-ionic (mannitol) osmotic stress. Mutations disrupted ABA induction of stomatal closure as well as ABA inhibition of light-induced stomatal opening. However, regulation of stomatal opening/closing by light or CO(2) is not affected in these mutants. May act in the interval between ABA perception and reactive oxygen species production in the ABA signalling network.

Activator of the abscisic acid (ABA) signaling pathway that regulates numerous ABA responses, such as stomata closure in response to drought, plant pathogens, or decreases in atmospheric relative humidity (RH). Involved in the resistance to drought by avoiding water loss. Required for the stomata closure mediated by pathogen-associated molecular pattern (PAMPs) (e.g. flg22 and LPS) of pathogenic bacteria such as P.syringae pv. tomato (Pst) and E.coli O157:H7. As a plant defense process, stomata are closed transiently in order to limit invaders, but actively reopened by bacteria after a few hours; virulent strains (e.g. Pst DC3000) are more efficient than avirulent strains (e.g. Pst DC3000 AvrRpt2) in reopening stomata. Mediates the phosphorylation and activation of the S-type anion efflux channel SLAC1, and thus promotes stomata closure. Essential for stomatal closure in response to reactive oxygen species (ROS). Promotes MAPKKK18 activity upon abscisic acid (ABA) treatment (PubMed:26443375).