Recombinant Human IL-6R alpha Fc Chimera Protein, CF

Interleukin-6 receptor subunit alpha (IL-6Ra), also known as membrane glycoprotein 80 (gp80), IL-6R 1 or CD126, is a single-pass type I membrane protein of the interleukin receptor family. Human IL-6Ra is an 80 kDa receptor component that binds IL-6 with low affinity and forms one-half of the IL-6R receptor complex. IL-6Ra associates with a non-ligand binding 130 kDa glycoprotein signal-transducing component (CD130; gp130) for high-affinity binding to IL-6 (1-4). When bound to IL-6, the IL-6R complex forms a trimer, which homodimerizes to form a hexameric cellular signaling complex (1, 4). Human IL-6Ra consists of an extracellular domain (ECD) with an N-terminal Ig-like C2-type domain and a cytokine-binding domain containing two fibronectin type-III domains with a WSXWS motif, a helical transmembrane segment and a cytoplasmic domain. Within the mature ECD, human IL-6Ra shares 51% and 52% amino acid sequence identity with mouse and rat IL-6Ra, respectively. Soluble forms of IL-6Ra can be generated via ADAM10 and ADAM17 cleavage of membrane bound IL-6Ra, alternative mRNA splicing and microvesicle release (3, 4). Unlike gp130 that is expressed ubiquitously, the cellular distribution of IL-6 R alpha is predominantly limited to hepatocytes and leukocyte subpopulations such as monocytes, neutrophils, T and B cells. Soluble IL-6R alpha has been found in various body fluids (5). It has been documented that elevated soluble IL-6 R is associated with numerous diseases including arthritic lesions, multiple myeloma and Crohn's disease (6, 7).