The function of Ensembl gene identifier ENSG00000204671 (IL31, interleukin 31) is as follows. Functions as a cytokine that binds to IL31RA, a membrane- bound signal-transducing subunit of the IL31 receptor complex (heterodimer composed of OSMR and IL31RA) (PubMed:15184896, PubMed:15627637). Functionally, IL31 signaling via OSMR/IL31RA is particularly important in skin immunity (PubMed:15184896). Mechanistically, ligand binding to IL31RA, induces heterodimerization with OSMR, activating JAK1 and JAK2 (and to a lesser extent TYK2) associated with the intracellular domains of IL31RA and OSMR (PubMed:15627637). These kinases phosphorylate tyrosine residues on IL31RA and OSMR, creating docking sites for STAT1, STAT3, and STAT5B, which are then phosphorylated and activated (PubMed:15184896, PubMed:15627637). In addition, the IL31 receptor complex activates the MAPK pathway (MAPK3/ERK1-MAPK1/ERK2) via recruitment of the adapter protein SHC1 (PubMed:15627637). Enhances myeloid progenitor cell survival in vitro (By similarity). Induces RETNLA and serum amyloid A protein expression in macrophages (By similarity). {ECO:0000250|UniProtKB:Q6EAL8, ECO:0000269|PubMed:15184896, ECO:0000269|PubMed:15627637}.