Phospho-TAK1 (Ser412) Antibody #9339

TAK1 is a mitogen-activated protein kinase kinase kinase that can be activated by TGF-β, bone morphogenetic protein, and other cytokines, including IL-1 (1,2). In vivo activation of TAK1 requires association with TAK1 binding protein 1 (TAB1), which triggers phosphorylation of TAK1 (3,4). Another adaptor protein, TAB2, links TAK1 with TRAF6 and mediates TAK1 activation upon IL-1 stimulation (5). Once activated, TAK1 phosphorylates MAPK kinases MKK4 and MKK3/6, which activate p38 MAPK and JNK, respectively. In addition, TAK1 activates the NF-κB pathway by interacting with TRAF6 and phosphorylating the NF-κB inducing kinase (NIK) (2).

TAK1 activation requires multiple phosphorylations in its activation loop. Mutations at Thr187 and Thr184, residues located in the activation loop of TAK1, impairs phosphorylation of both TAK1 and TAB1 and reduces the kinase activity of TAK1, suggesting that autophosphorylation of these residues is necessary for TAK1 activation (4). TAK1 is also phosphorylated at Ser412 in a PKA-dependent manner (6). A mutation of Ser412 to alanine acts as a dominant negative for PKA-enhanced degradation of IκBα, phosphorylation of p38 MAPK and prostaglandin E2-enhances osteoclastic differentiation in RAW264.7 cells (6).