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Publication Abstract from PubMed

The neonatal Fc receptor (FcRn) transports maternal immunoglobulin G (IgG) to the bloodstream of the newborn. FcRn is structurally similar to class I major histocompatibility complex (MHC) molecules, despite differences in the ligands they bind (the Fc portion of IgG and antigenic peptides, respectively). A low-resolution crystal structure of the complex between FcRn and Fc localizes the binding site for Fc to the side of FcRn, distinct from the tops of the alpha 1 and alpha 2 domains which serve as the peptide and T-cell receptor binding sites in class I molecules. FcRn binds to Fc at the interface between the Fc CH2 and CH3 domains, which contains several histidine residues that could account for the sharply pH-dependent FcRn/IgG interaction. A dimer of FcRn heterodimers observed in the co-crystals and in the crystals of FcRn alone could be involved in binding Fc, correlating with the 2:1 binding stoichiometry between FcRn and IgG (ref. 4) and suggesting an unusual orientation of FcRn on the membrane.

Crystal structure of the complex of rat neonatal Fc receptor with Fc.,Burmeister WP, Huber AH, Bjorkman PJ Nature. 1994 Nov 24;372(6504):379-83. PMID:7969498^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.