• IL20RA is mainly expressed in epithelial cells and forms the functional receptor, when heterodimerized with interleukin 20 receptor subunit beta (IL20RB), to bind immune cell-produced IL-20 subfamily of cytokines IL-19, IL-20, and IL-24, which have essential roles in regulating epithelial innate immunity and tissue repair.
• IL-20 receptor alpha (IL-20 R alpha ), also named IL-20 R1, CRF2-8, and ZCYTOR7, belongs to the class II cytokine receptor family, which includes 12 members. These receptors are characterized by the patterns of conserved amino acid (aa) residues in their extracellular domains, which are composed of tandem fibronectin type III domains.
• Mouse Il20ra mRNA was detectable in wild-type mice. Human IL20RA mRNA was detectable only in homozygous B-hIL20RA mice (H/H) but not in wild-type mice.

Gene targeting strategy for B-hIL20RA mice. The exons 2-6 of mouse Il20ra gene that encode extracellular domain are replaced by human counterparts in B-hIL20RA mice. The genomic region of mouse Il20ra gene that encodes transmembrane domain and cytoplasmic portion is retained. The promoter, 5’UTR and 3’UTR region of the mouse gene are also retained. The chimeric IL20RA expression is driven by endogenous mouse Il20ra promoter, while mouse Il20ra gene transcription and translation will be disrupted.

Strain specific analysis of IL20RA mRNA expression in wild-type C57BL/6N mice and B-hIL20RA mice by RT-PCR. Lung RNA were isolated from wild-type C57BL/6N mice (+/+) and homozygous B-hIL20RA mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human IL20RA primers. Mouse Il20ra mRNA was detectable in wild-type mice. Human IL20RA mRNA was detectable only in homozygous B-hIL20RA mice (H/H) but not in wild-type mice.