Binds to folate and reduced folic acid derivatives and mediates delivery of 5-methyltetrahydrofolate and folate analogs into the interior of cells (PubMed:1894617). Has high affinity for folate and folic acid analogs at neutral pH (By similarity). Exposure to slightly acidic pH after receptor endocytosis triggers a conformation change that strongly reduces its affinity for folates and mediates their release (By similarity). Required for normal embryonic development and normal cell proliferation (PubMed:10508523, PubMed:12854656, PubMed:15259034, PubMed:17286298). Required for renal folate reabsorption (PubMed:15703271). Endocytosed into cytoplasmic vesicles and then recycled to the cell membrane. Detected in kidney proximal tubules (at protein level). The secreted form is derived from the membrane-bound form either by cleavage of the GPI anchor, or/and by proteolysis catalyzed by a metalloprotease. Embryonic lethality at about 10.5 dpc, due to gross developmental defects, including defects of neural tube closure, craniofacial defects and defects in heart development. Embryos can be rescued by maternal folate supplementation. Belongs to the folate receptor family.