[Isoform 1]: Functions as a membrane-bound signal-transducing subunit either in complex with IL6ST/gp130 or as part of the ciliary neurotrophic factor receptor (CNTFR) complex composed by CNTFR, IL6ST/gp130 and LIFR (PubMed:11285233, PubMed:11294841, PubMed:1542794, PubMed:39532904, PubMed:9030543, PubMed:9188471). Signal transmission is initiated either by binding directly to cytokines, such as OSM or LIF or CTF1, or through the binding of other cytokines, like CNTF, CLCF1 or the heterodimeric complex CRLF1-CLCF1 to the non-signaling receptor CNTFR; ligand binding induces heterodimerization of IL6ST/gp130 and LIFR which activates JAK tyrosine kinases bound to their intracellular domains (PubMed:11285233, PubMed:11294841, PubMed:1542794, PubMed:1915266, PubMed:9030543, PubMed:9188471). These kinases subsequently phosphorylate the homodimer or heterodimer form of IL6ST/gp130 (PubMed:11285233, PubMed:11294841, PubMed:9030543). The tyrosine phosphorylated signaling receptors serve in turn as docking sites for recruitment and activation of signal transducer and activators of transcription (STATs) (PubMed:11285233, PubMed:11294841, PubMed:9030543, PubMed:9188471). Engages sites 3 of ligands cytokines (PubMed:36930708). {ECO:0000269|PubMed:11285233, ECO:0000269|PubMed:11294841, ECO:0000269|PubMed:1542794, ECO:0000269|PubMed:1915266, ECO:0000269|PubMed:36930708, ECO:0000269|PubMed:39532904, ECO:0000269|PubMed:9030543, ECO:0000269|PubMed:9188471}. [Isoform 2]: Could inhibit the biological activity of LIF by blocking its binding to receptors on target cells. . This is the function of ENSG00000113594 (LIFR, LIF receptor subunit alpha).