Neonatal Fc receptor alpha chain (FCGRT) (FCGRT)

The Neonatal Fc receptor alpha chain (FCGRT), also known as the p51 subunit, is a transmembrane glycoprotein that associates with beta-2-microglobulin to form the functional FcRn complex (UniProt: P55899). Structurally similar to MHC class I molecules, FcRn is responsible for the pH-dependent recycling of immunoglobulin G (IgG) and albumin, protecting them from lysosomal degradation and significantly extending their half-life in circulation (PubMed: 26048911). In autoimmune diseases, this mechanism unfortunately preserves pathogenic autoantibodies, contributing to disease progression (PubMed: 31110339). Therapeutic strategies involve using FcRn antagonists, such as efgartigimod or rozanolixizumab, which bind to the alpha chain and block the interaction with the Fc region of IgG (DrugBank: DB15581). This blockade results in the rapid clearance of IgG from the blood, providing a targeted treatment for conditions like myasthenia gravis and immune thrombocytopenia (PubMed: 34197152).

Other names

FcRn large subunit p51IgG receptor FcRn large subunit p51Neonatal Fc receptor alpha chainFCGRTp51 subunitMajor histocompatibility complex class I-related gene protein

FcRn antagonism; competitive inhibition of the neonatal Fc receptor alpha chain to prevent IgG recycling and promote lysosomal degradation of pathogenic IgG autoantibodies (PubMed: 31110339).