Interleukin-6 Receptor Alpha, also known as IL-6RA, IL-6R1 and CD126, belongs to the type I cytokine receptor family. It is mainly expressed on T cells, fibroblasts and macrophages. IL-6RA couples with gp130 to form the IL-6 receptor; IL-6RA binds specifically to IL-6 and depends on gp130 to transmit signals. IL-6RA dysfunction has been correlated with the pathogenesis of many diseases, such as multiple myeloma, autoimmune diseases and prostate cancer. Soluble IL-6RA, which consists of only the extracellular domain of IL-6RA, acts as an agonist of IL-6 activity.

> 95% as determined by SDS-PAGE; > 95% as determined by HPLC