Fc fragment of IgG receptor and transporter | Immunoglobulin C1-set domain-containing proteins | IUPHAR Guide to IMMUNOPHARMACOLOGY

Top ▲

Fc fragment of IgG receptor and transporter

  Target has curated data in GtoImmuPdb

Target id: 2985

Nomenclature: Fc fragment of IgG receptor and transporter

Abbreviated Name: FcRn

Family: Immunoglobulin C1-set domain-containing proteins

Annotation status:  image of a grey circle Awaiting annotation/under development. Please contact us if you can help with annotation.  » Email us

Gene and Protein Information
Species TM AA Chromosomal Location Gene Symbol Gene Name Reference
Human 1 365 19q13.33 FCGRT Fc fragment of IgG receptor and transporter
Mouse 1 365 7 B3; 7 29.12 cM Fcgrt Fc receptor, IgG, alpha chain transporter
Rat 1 366 1q22 Fcgrt Fc fragment of IgG receptor and transporter
Previous and Unofficial Names
Fc receptor, IgG, alpha chain transporter | Fc receptor | Fc fragment of IgG, receptor, transporter, alpha | heavy chain of the major histocompatibility complex class I-like Fc receptor | IgG receptor FcRn large subunit p51 | neonatal Fc receptor
Database Links
ChEMBL Target
Ensembl Gene
Entrez Gene
Human Protein Atlas
RefSeq Nucleotide
RefSeq Protein
Selected 3D Structures
Image of receptor 3D structure from RCSB PDB
Description:  Crystal structure of Fab fragment of antibody DX-2507 bound to FcRn-B2M.
Ligand:  DX-2507
Resolution:  2.5Å
Species:  Human
References:  3

Download all structure-activity data for this target as a CSV file

Key to terms and symbols Click column headers to sort
Antibody Sp. Action Value Parameter Reference
DX-2507 Hs Antagonist 8.7 pKd 6
pKd 8.7 (Kd 1.8x10-9 M) [6]
Description: Binding affinity at acidic pH (6.0).
rozanolixizumab Hs Binding ~8.2 – 8.7 pKd 1
pKd ~8.2 – 8.7 (Kd ~6x10-9 – 2x10-9 M) [1]
Description: In a cell- based in vitro assay using neutral buffer. Note this affinity range is for the 01519.g57 Fab or PEGylated Fab fragment, not the intact IgG4P antibody.
efgartigimod alfa Hs Binding - - 7
Antibody Comments
The FcRn binding affinity (Kd) of DX-2507 at neutral pH is 2 nM [6].
Immunopharmacology Comments
FcRn is important for developing immunity in the fetus and neonate (transporting IgG from mother to fetus and neonate for passive immunity) [2], for the development of adaptive immunity, and for regulating IgG levels (protecting IgG catabolism) in the mature immune system [4]. FcRn expression is upregulated by TNF-α (a proinflammatory cytokine) and downregulated by IFN-γ (an anti-inflammatory cytokine) [5]. In some autoimmune diseases levels of pathogenic IgG autoantibodies are elevated, and their long half-lives and prolonged action are a result of FcRn-mediated protection from degradation. For this reason inhibition of FcRn is viewed as an attractive clinical intervention for IgG-mediated autoimmune diseases [4-5]. FcRn antagonism may also be a strategy applicable to the management of neutralising anti-drug antibodies that can develop in patients receiving biologic/enzyme replacement therapies. Examples of anti-FcRn therapeutics in development pipelines include rozanolixizumab (Phase 2; UCB Pharma), efgartigimod alfa (Phase 2; Argenx), M281 (nipocalimab; Phase 2; Momenta Pharmaceuticals), SYNT001 (Phase 1; Syntimmune) and DX-2507 (preclinical; Shire).
Immuno Process Associations
Immuno Process:  Immune regulation
GO Annotations:  Associated to 1 GO processes
GO:0019770 IgG receptor activity TAS
Immuno Process:  Antigen presentation
GO Annotations:  Associated to 1 GO processes
GO:0002476 antigen processing and presentation of endogenous peptide antigen via MHC class Ib IBA
Immuno Process:  Cellular signalling
GO Annotations:  Associated to 1 GO processes
GO:0019770 IgG receptor activity TAS


Show »

1. Finney HM, Lawson ADG, Shaw SG, Smith BJ, Tyson KL, Kevorkian L. (2014) Anti-fcrn antibodies. Patent number: WO2014019727. Assignee: Ucb Pharma S.A.. Priority date: 14/05/2012. Publication date: 06/02/2014.

2. Jones EA, Waldmann TA. (1972) The mechanism of intestinal uptake and transcellular transport of IgG in the neonatal rat. J. Clin. Invest., 51 (11): 2916-27. [PMID:5080417]

3. Kenniston JA, Taylor BM, Conley GP, Cosic J, Kopacz KJ, Lindberg AP, Comeau SR, Atkins K, Bullen J, TenHoor C et al.. (2017) Structural basis for pH-insensitive inhibition of immunoglobulin G recycling by an anti-neonatal Fc receptor antibody. J. Biol. Chem., 292 (42): 17449-17460. [PMID:28878017]

4. Kuo TT, Aveson VG. (2011) Neonatal Fc receptor and IgG-based therapeutics. MAbs, 3 (5): 422-30. [PMID:22048693]

5. Kuo TT, Baker K, Yoshida M, Qiao SW, Aveson VG, Lencer WI, Blumberg RS. (2010) Neonatal Fc receptor: from immunity to therapeutics. J. Clin. Immunol., 30 (6): 777-89. [PMID:20886282]

6. Nixon AE, Chen J, Sexton DJ, Muruganandam A, Bitonti AJ, Dumont J, Viswanathan M, Martik D, Wassaf D, Mezo A et al.. (2015) Fully human monoclonal antibody inhibitors of the neonatal fc receptor reduce circulating IgG in non-human primates. Front Immunol, 6: 176. [PMID:25954273]

7. Ulrichts P, Cousin T, Dreier T, de Haard H, Leupin N. (2016) Argx-113, a Novel Fc-Based Approach for Antibody-Induced Pathologies Such As Primary Immune Thrombocytopenia. Blood, 128: 4919.

How to cite this page

Immunoglobulin C1-set domain-containing proteins: Fc fragment of IgG receptor and transporter. Last modified on 05/08/2019. Accessed on 04/08/2020. IUPHAR/BPS Guide to PHARMACOLOGY, http://www.guidetoimmunopharmacology.org/GRAC/ObjectDisplayForward?objectId=2985.