catalytic activity:ATP + a protein = ADP + a phosphoprotein.,enzyme regulation:p38 alpha and beta-dependent phosphorylation increases its activity. Activated by stress-related extracellular stimuli; such as H(2)O(2), arsenite, anisomycin TNF alpha and also PMA and the calcium ionophore A23187; but to a lesser extent. In vitro, activated by SQSTM1.,function:Mediates stress-induced small heat shock protein 27 phosphorylation.,PTM:Phosphorylated on Thr-182; which is the regulatory phosphorylation site and is located on the T-loop/loop 12.,similarity:Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family.,similarity:Contains 1 protein kinase domain.,subcellular location:Also observed in the nucleus.,subunit:Interacts with SQSTM1.,tissue specificity:Expressed ubiquitously.,
Cytoplasm. Nucleus. Translocates to the cytoplasm following phosphorylation and activation. Interaction with ERK3/MAPK6 or ERK4/MAPK4 and phosphorylation at Thr-182, activates the protein kinase activity, followed by translocation to the cytoplasm. Phosphorylation by PKA/PRKACA at Ser-115 also induces nuclear export.