Interleukin 1 2 haivates Two Forms of p 54 a Mitogen - activated Protein K inase in Rabbit Liver

We have identified in rabbits two hepatic forms of T669 peptide kinases that are very strongly activated after systemic injection with the inflammatory cytokiue interleukin 1 (ID1). The T669 peptide contains a major phosphoryhtion site of the epidermal growth factor receptor, threonine 699 and is a substrate for mitogen-activated protein (MAP) kinases. The kinases were purified to homogeneity and corresponded to 50and 55-kD proteins on sodium dodecyl sulfate-polyaerylamide gel electrophoresis. Amino add sequencing of 12 tryptic peptides of both kinases identified them as p54 MAP kinase or. This kinase belongs to the novel family of stress-activated protein kinag's. This is the first evidence of IL-1 activating a spedfic protein kinase in vivo.