Human IL‑13 R alpha 2 Fluorescein‑conjugated Antibody

Two type1 membrane proteins belonging to the Hemopoietin Receptor family have been cloned and shown to bind IL-13 with differing affinities. The lower affinity IL-13 binding protein, previously designated IL-13 R alpha, IL-13 R alpha ' or NR4, is now referred to as IL-13 R alpha 1. The high affinity IL-13 binding protein, previously also designated IL-13 R or IL-13 R alpha ', is now referred to as IL-13 R alpha 2. Human IL-13 R alpha 2 was originally cloned from the Caki-1 human renal carcinoma cell line. The IL-13 R alpha 2 cDNA encodes a 380 amino acid (aa) residue precursor protein with a putative 26 aa residue signal peptide, a 317 residue extracellular domain, a 20 aa residue transmembrane region and a 17 aa residue cytoplasmic tail. Human and mouse IL-13 R alpha 2 share 59% aa sequence identity. The extracellular domain of IL-13 R alpha 2 is also closely related to that of IL-13 R alpha 1. However, the 17 aa residue cytoplasmic domain of IL-13 R alpha 2 is much shorter than that of IL-13 R alpha 1, suggesting that the two receptors are functionally distinct. IL-13 R alpha 1 has been shown to combine with the IL-4 R to form a high-affinity receptor complex capable of transducing an IL‑13‑dependent proliferative signal. The role of IL-13 R alpha 2 in IL-13 signaling remains to be elucidated. The amino-terminal 27 aa residues of the human and mouse IL‑13 R alpha 2 are nearly identical to that of a soluble mouse IL-13 binding protein purified from mouse serum and urine.