Eukaryotic Interleukin 18 (IL18)

Function

Pro-inflammatory cytokine primarily involved in epithelial barrier repair, polarized T-helper 1 (Th1) cell and natural killer (NK) cell immune responses (PubMed:10653850). Upon binding to IL18R1 and IL18RAP, forms a signaling ternary complex which activates NF-kappa-B, triggering synthesis of inflammatory mediators (PubMed:14528293, PubMed:25500532, PubMed:37993714). Synergizes with IL12/interleukin-12 to induce IFNG synthesis from T-helper 1 (Th1) cells and natural killer (NK) cells (PubMed:10653850). Involved in transduction of inflammation downstream of pyroptosis: its mature form is specifically released in the extracellular milieu by passing through the gasdermin-D (GSDMD) pore (PubMed:33883744)

Subcellular Location

Cytoplasm, cytosol; Secreted

Tissue Specificity

Expressed in ovarian carcinoma but undetectable in normal ovarian epithelial cells. Resistant to proteolytic activation by caspase-1 and -4

Subunit

Forms a ternary complex with ligand-binding receptor subunit IL18R1 and signaling receptor subunit IL18RAP at the plasma membrane (PubMed:14528293, PubMed:25261253, PubMed:25500532, PubMed:37993714). Mature IL18 first binds to IL18R1 forming a low affinity binary complex, which then interacts with IL18RAP to form a high affinity ternary complex that signals inside the cell (PubMed:14528293, PubMed:25261253, PubMed:25500532). Interacts with cargo receptor TMED10; the interaction mediates the translocation from the cytoplasm into the ERGIC (endoplasmic reticulum-Golgi intermediate compartment) and thereby secretion (PubMed:32272059)

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• Mural R.J. et al. PubMed: CI-56FT96O07V0QG (JUL-)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)