Granulocyte-Macrophage Colony-Stimulating Factor Receptor Subunit α (CSF2RA) is a single-pass type I membrane protein which belongs to the type I cytokine receptor family of Type 5 subfamily. The CSF2RA gene is found in the pseudoautosomal region (PAR) of the X and Y chromosomes with some of the isoforms being membrane-bound and others being soluble. CSF2RA is a low affinity receptor for granulocyte-macrophage colony-stimulating factor. CSF2RA transduces a signal that results in the proliferation, differentiation, and functional activation of hematopoietic cells. Defects in CSF2RA are the cause of pulmonary surfactant metabolism dysfunction type 4 (SMDP4).