Crystal structure at 2.2 Å resolution of the MHC-related neonatal Fc receptor
The three-dimensional structure of the rat neonatal Fc receptor (FcRn) is similar to the structure of molecules of the major histocompatibility complex (MHC). The counterpart of the MHC peptide-binding site is closed in FcRn, making the FcRn groove incapable of binding peptides. A dimer of FcRn heterodimers seen in the crystals may represent a receptor dimer that forms when the Fc portion of a single immunoglobulin binds. An alternative use of the MHC fold for immune recognition is indicated by the FcRn and FcRn/Fc co-crystal structures.
© 1994 Nature Publishing Group. Received 29 June; accepted 6 October 1994. We thank P. Tsun for processing the P2_1 data, A. Huber for help with data collection and figures; the staff at CHESS, A. Mondragon, M. Raghavan and D. Rees for critical reading of the manuscript, M. Chen for help with figures; L. Stern for the MHC class II coordinates; and A. Mondragón for discussion. Coordinates will be deposited in the Brookhaven databank or can be requested by e-mail (burmeister@ citray.caltech.edu). This work was supported by the Howard Hughes Medical Institute (P.J.B.), an EMBO fellowship (W.P.B.), the CNRS (L.N.G.), the Beckman Institute (M.L.B.), the NIH (N.E.S.) and the March of Dimes Birth Defects Foundation (N.E.S.). Some of the refinement was run on a CRAY-YMP at the San Diego Supercomputer Center, supported by the NSF.