Fig. 3. The organization of protein modules in the extracellular domains of gp130 family receptors (see Table I). The receptors are generated from three modules: the cytokine receptor homology domain (CHD), the IG-like domain (IGD) and three copies of a fibronectin type III repeat (FNIII). (A) gp130; (B) the LIF-R; (C) the OSM-R; (D) soluble receptors (CNTF-R, IL-6R, IL-11R).