IL-18R alpha Protein, Human (HEK293, His-Avi)

IL-18R alpha (interleukin-18 receptor alpha) is an interleukin receptor of the immunoglobulin superfamily. IL-18 forms a signalling complex with the IL-18 receptor α (Rα) and β (Rβ) chains at the plasma membrane, which induces multiple inflammatory cytokines^[1]. IL-18R complex recruits the IL-1R- activating kinase and TNF- associated factor 6, which phosphorylates nuclear factor kβ- inducing kinase, with subsequent activation of nuclear factor kβ^[2]. IL-18R alpha inhibits the production of IFN-γ stimulated with the combination of rhIL-2 and rhIL-18^[3]. IL-18R alpha Protein, Human (HEK293, His-Avi) is a recombinant protein with a His-Avi label that consists of 311 amino acids (A19-R329) and is produced by HEK293 cells.

IL-18R alpha is expressed on CD4⁺ and CD8⁺ T cells but not expressed on naive T cells^[4].
The amino acid sequence of human IL-18R alpha protein has low homology for mouse IL-18R alpha protein.
IL-18R alpha is the receptor of IL-18. IL-18 is extracellularly secreted and binds IL-18 receptor α (Rα) as well as IL-18 receptor β (Rβ) at the immunocyte plasma membrane in a stepwise manner. IL-18/IL-18Rα/IL-18Rβ ternary complex formation juxtaposes the intracellular Toll-Interleukin-1 receptor domains of IL-18Rα and IL-18Rβ. Then, the adaptor molecule myeloid differentiation factor 88 (MyD88) is recruited presumably with the aid of TRAM. MyD88 further interacts with IL-1 receptor associating kinase (IRAK) 4 and IRAK1/2 to form the large molecular assembly referred to as Myddosome, which subsequently activates IKK via TRAF6. Finally, the signal activates the NF-κB and mitogen-activated protein kinase pathways7, which upregulate the expression of various inflammatory cytokines^[1].
IL-18R alpha binds to IL-18 and IL-18 receptor β forms a signalling complex induces the expression of various inflammatory cytokines^[1]. IL-18R alpha inhibits the production of IFN-γ stimulated with the combination of rhIL-2 and rhIL-18^[3].

IL-18R alpha (human) (0.1, 1, 10 µg/mL) inhibits the production of IFN-γ by NK0 cells stimulated with the combination of rhIL-2 (50 IU/mL) and rhIL-18 (50 ng/mL) by 0%, 2% and 34%, respectively^[3].

Measured by its binding ability in SPR assay. Human IL-18 R1, His Tag immobilized on CM5 Chip can bind Human IL-18, No Tag with an affinity constant < 8 nM.

Human

HEK293

C-Avi;C-His

Q13478 (A19-R329)

8809  [NCBI]

60-70 kDa

Greater than 95% as determined by Tris-Bis PAGE.

Lyophilized powder.

Lyophilized from a 0.22 μm filtered solution of PBS, pH 7.4. Normally 5% trehalose is added as protectant before lyophilization.

<1 EU/μg, determined by LAL method.

It is not recommended to reconstitute to a concentration less than 100 μg/mL in ddH₂O.

Stored at -20°C for 2 years. After reconstitution, it is stable at 4°C for 1 week or -20°C for longer (with carrier protein). It is recommended to freeze aliquots at -20°C or -80°C for extended storage.

Room temperature in continental US; may vary elsewhere.

• [1]. Tsutsumi N, et al. The structural basis for receptor recognition of human interleukin-18. Nat Commun. 2014 Dec 15;5:5340.  [Content Brief]

  [2]. Watanabe M, et al. Predominant expression of 950delCAG of IL-18R alpha chain cDNA is associated with reduced IFN-gamma production and high serum IgE levels in atopic Japanese children. J Allergy Clin Immunol. 2002 Apr;109(4):669-75.  [Content Brief]

  [3]. Takei S, et al. Soluble interleukin-18 receptor complex is a novel biomarker in rheumatoid arthritis. Arthritis Res Ther. 2011 Mar 24;13(2):R52.  [Content Brief]

  [4]. Smeltz RB, et al. Regulation of interleukin (IL)-18 receptor alpha chain expression on CD4(+) T cells during T helper (Th)1/Th2 differentiation. Critical downregulatory role of IL-4. J Exp Med. 2001 Jul 16;194(2):143-53.  [Content Brief]