Platelet-derived growth factor receptor alpha (PDGFRA), also known as CD140a, together with the structurally homolog protein PDGFRB (CD140b), are members of the class III subfamily of receptor tyrosine kinases (RTK) that also includes the receptors for M-CSF, SCF, and Flt-3 ligand. All class III RTKs are characterized by the presence of five immunoglobulin-like domains in their extracellular region and a kinase domain in their intracellular region. PDGFRA is expressed in oligodendrocyte progenitor cells and mesothelial cell, and binds all three ligand isoforms PDGF-AA, PDGF-BB and PDGF-AB with high affinity. PDGFRA plays an essential role in regulating proliferation, chemotaxis and migration of mesangial cells. Recent studies have indicated that PDGFRA acts as a critical mediator of signaling in testis organogenesis and Leydig cell differentiation. In knockout mice, it is suggested that PDGFRA is particularly important for kidney development since mice heterozygous for the receptor exhibit defective kidney phenotypes.