Folate receptors bind folate and reduced folic acid

Folic acid

Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9...

 derivatives and mediates delivery of tetrahydrofolate to the interior of cells. It is then converted from monoglutamate to polyglutamate forms - such as 5- methyltetrahydrofolate - as only monoglutamate forms can be transported across cell membranes. Polyglutamate forms are biologically active enzymatic cofactors required for many folate-dependent processes such as folate-dependent one-carbon metabolism. These proteins are attached to the membrane by a GPI anchor. A riboflavin

Riboflavin

Riboflavin, also known as vitamin B2 or additive E101, is an easily absorbed micronutrient with a key role in maintaining health in humans and animals. It is the central component of the cofactors FAD and FMN, and is therefore required by all flavoproteins. As such, vitamin B2 is required for a...

-binding protein required for the transport of riboflavin to the developing oocyte in chicken also belong to this family.

Human proteins from this family include Folate receptor 1 (adult), Folate receptor 2 (fetal)

FOLR2

Folate receptor beta is a protein that in humans is encoded by the FOLR2 gene.-Further reading:...

, FOLR3 and RTBDN.