In complex with CLCF1, forms a heterodimeric neurotropic cytokine that plays a crucial role during neuronal development (Probable). May also play a regulatory role in the immune system. Forms covalent di- and tetramers. Forms a heteromeric complex with cardiotrophin-like cytokine CLCF1/CLC; the CRLF1-CLCF1 complex is a ligand for the ciliary neurotrophic factor receptor/CNTFR (PubMed:9686600, PubMed:26858303). The CRLF1-CLCF1 heterodimer binds SORL1 (via N-terminal ectodomain); within this complex, the interaction is mediated predominantly by the CRLF1 moiety (PubMed:26858303). The tripartite signaling complex formed by CRLF1, CLCF1 and CNTFR also binds SORL1 (PubMed:26858303). Highest levels of expression observed in spleen, thymus, lymph node, appendix, bone marrow, stomach, placenta, heart, thyroid and ovary. Strongly expressed also in fetal lung. Up-regulated in fibroblast primary cell cultures under stimulation by IFNG/IFN-gamma, TNF and IL6/interleukin-6. The WSXWS motif appears to be necessary for proper protein folding and thereby efficient intracellular transport and cell-surface receptor binding. The disease is caused by variants affecting the gene represented in this entry. Belongs to the type I cytokine receptor family. Type 3 subfamily.