Signal transduction by the IL-1 type I receptor: evidence for the involvement of a receptor-coupled protein kinase.

A novel serine/threonine specific protein kinase was found to be associated with the type I IL-1 receptor in the murine T cell lines D10N and EL-4. This kinase was identified in immunoprecipitates from IL-1 stimulated T-cells by its ability to phosphorylate exogenous substrates in the presence of radiolabeled ATP. An endogenous protein, most likely a member of the IL-1 R1 complex, was also phosphorylated. The activation of the kinase is specific for IL-1, neither TNF nor phorbol esters were able to activate the IL-1 RI associated kinase activity. The IL-1 receptor antagonist had no intrinsic activity and inhibited the activation of the kinase. The activation of the kinase was rapid and detectable after 30 seconds of IL-1 stimulation. A minimal model of the IL-RI signal transduction complex is discussed, presenting this novel serine/threonine kinase as a constituent of the complex.