Binds to folate and reduced folic acid derivatives and mediates delivery of 5-methyltetrahydrofolate and folate analogs into the interior of cells. Has high affinity for folate and folic acid analogs at neutral pH. 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 (By similarity). Endocytosed into cytoplasmic vesicles and then recycled to the cell membrane. Detected in milk (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. Belongs to the folate receptor family.