Folate receptor gamma (FOLR3) (FOLR3)

Folate receptor gamma (FOLR3) is a high-affinity folate-binding protein that is uniquely characterized among the folate receptor family by its lack of a glycosylphosphatidylinositol (GPI) anchor, resulting in its constitutive secretion as a soluble protein (UniProt P41439). It is primarily expressed in hematopoietic tissues, including the spleen, thymus, and bone marrow, and is often upregulated in certain leukemias and other malignancies (PubMed: 10451252). While its primary biological role involves the binding and transport of folates to maintain cellular homeostasis, its presence in the serum makes it a potential biomarker for specific cancers. In the context of drug development, FOLR3 is being explored as a target for folate-conjugated therapeutics and monoclonal antibodies, although it is less frequently targeted than its membrane-bound counterparts, Folate receptor alpha and beta (NCBI Gene: 2352). The protein's high affinity for folic acid and reduced folates like methotrexate allows it to influence the pharmacokinetics of antifolate drugs (PubChem CID: 5950). Its soluble nature suggests it may act as a carrier or a scavenger for folates in the extracellular environment, distinguishing it from the receptor-mediated endocytosis pathways of FR-alpha and FR-beta. Research indicates that FOLR3 expression is highly restricted in normal tissues but significantly elevated in patients with chronic myelogenous leukemia (CML) and acute myeloid leukemia (AML), providing a window for targeted intervention (PubMed: 10451252).

Other names

FOLR3Folate receptor 3FR-gammaGamma-folate receptorFolate-binding protein 3

FOLR3 acts by binding to extracellular folates with high affinity, thereby regulating the availability of these essential vitamins for cellular uptake; in a therapeutic context, it can sequester antifolate drugs or be used to facilitate the delivery of folate-conjugated agents to hematopoietic cells (UniProt P41439, PubMed 10451252).