This domain can be found in leukemia inhibitory factor receptor (LIFR). LIFR is a cell surface receptor that mediates the actions of LIF and other interleukin-6 type cytokines through the formation of signalling complexes with gp130. This is the N-terminal domain, referred to as domain 1, which contains conserved disulfide bonds between Cys-10 to Cys-20 and Cys-37 to Cys-45 [1].

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