Catalytic domain of the Serine/Threonine Kinase, Plant Mitogen-Activated Protein (MAP)/Extracellular signal-Regulated Kinase (ERK) Kinase Kinase 1
STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. This subfamily is composed of plant MAPK kinase kinases (MAPKKKs) including Arabidopsis thaliana MEKK1 and MAPKKK3. Arabidopsis thaliana MEKK1 activates MPK4, a MAPK that regulates systemic acquired resistance. MEKK1 also participates in the regulation of temperature-sensitive and tissue-specific cell death. MAPKKKs phosphorylate and activate MAPK kinases, which in turn phosphorylate and activate MAPKs during signaling cascades that are important in mediating cellular responses to extracellular signals. The plant MEKK1 subfamily is part of a larger superfamily that includes the catalytic domains of other STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
Jiyao W et al.(2023). "The conserved domain database in 2023.",