Granulocyte-macrophage colony-stimulating factor receptor subunit alpha (GM-CSF Receptor α), also known as CSF2RA and CD116, is a type 1 transmembrane protein with low affinity for GM-CSF. GM-CSF Receptor α is primarily expressed on myeloid cells, including granulocytes, monocytes, macrophages, and dendritic cells. GM-CSF Receptor α forms a heterodimeric receptor complex with GM-CSF Receptor β, creating the high affinity GM-CSF receptor. Upon dimerization and ligand binding, the β subunit becomes phosphorylated and transduces signals via Jak/STAT and MAPK pathways for cell proliferation, differentiation, and survival. Oligomerization of the high affinity GM-CSF Receptor α/β complex is required for optimal intracellular signal transduction. Soluble GM-CSF Receptor α, either secreted or cleaved from the cell surface, can competitively bind GM-CSF, preventing membrane receptor signaling. Multiple isoforms of GM-CSF Receptor α have been described.