This domain is found in Leukemia inhibitory factor receptor from mouse (LIF-R) and similar proteins from animals. LIF-R binds a cytokine that acts on many cell types including embryonic stem cells, megakaryocytes, osteoblasts, and neuronal cells. The extracellular region of this protein shows a modular structure with two cytokine-binding modules (CBM, with Pfam:PF17971 representing the second subdomain of CBM1, D2) separated by an Ig-like domain (this entry) and followed by three membrane- proximal fibronectin type-III (FNIII) domains (Pfam:PF00041) This domain interacts directly with site 3 of Cilliary Neutrophic Factor (CNTF) [1,2].

1: An unusual cytokine:Ig-domain interaction revealed in the crystal structure of leukemia inhibitory factor (LIF) in complex with the LIF receptor. Huyton T, Zhang JG, Luo CS, Lou MZ, Hilton DJ, Nicola NA, Garrett TP; Proc Natl Acad Sci U S A. 2007;104:12737-12742. PMID:17652170

2: Structural organization of a full-length gp130/LIF-R cytokine receptor transmembrane complex. Skiniotis G, Lupardus PJ, Martick M, Walz T, Garcia KC; Mol Cell. 2008;31:737-748. PMID:18775332