Interleukin-3 receptor (IL-3R) is a heterodimer that comprises an IL-3 specific alpha chain (IL-3R alpha) and a common beta chain (beta C) that is shared with the receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-5. The beta c subunit does not bind any cytokine by itself but is involved in the formation of high-affinity functional receptors for IL-5 and GM-CSF. These receptors belong to the cytokine receptor superfamily, but they are structurally and functionally more related to each other and thus make up a distinct subfamily.

> 95% as determined by Bis-Tris PAGE; > 90% as determined by HPLC