Meta-Biol

• Pathways

TBK1 activity is regulated by phosphorylation of Ser-172 within the kinase activation loop [Kishore N et al 2002]. TBK1 phosphorylation is thought to be an autoactivation event. Biochemical analysis demonstrated that the kinase domain alone was sufficient to fully autoactivate TBK1 and was capable of phosphorylating both macromolecular and peptide substrates [Ma X et al 2012]. Furthermore, TBK1 can autophosphorylate at Ser-172 and autoactivate when overexpressed in HEK293 cells. Additionally, in co-transfection experiments wild type TBK1 associated with and phosphorylated the catalytically inactive mutant TBK1-(K38A) at Ser-172 [Clark K et al 2009]. Studies of the crystal structure of TBK1 in complex with a potent small-molecule inhibitor BX795 revealed that Ser-172 from one protomer is located in close proximity to the active site of the neighboring protomer, providing a snapshot of a potential transautoactivation reaction intermediate [Ma X et al 2012]. However, involvement of a distinct upstream activating kinase in the TBK1 phosphorylation should not be ruled out [Clark K et al 2009].