ASSOCIATION AND ACTIVATION OF JAK-TYK KINASES BY CNTF-LIF-OSM-IL-6 BETA-RECEPTOR COMPONENTS

A recently defined family of cytokines, consisting of ciliary neurotro phic factor (CNTF), leukemia inhibitory factor (LIF), oncostatin M (OS M), and interleukin-6 (IL-6), utilize the Jak-Tyk family of cytoplasmi c tyrosine kinases. The beta receptor components for this cytokine fam ily, gp130 and LIF receptor beta, constitutively associate with Jak-Ty k kinases. Activation of these kinases occurs as a result of ligand-in duced dimerization of the receptor beta components. Unlike other cytok ine receptors studied to date, the receptors for the CNTF cytokine fam ily utilize all known members of the Jak-Tyk family, but induce distin ct patterns of Jak-Tyk phosphorylation in different cell lines.