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Analysis of the pH Dependence of the Neonatal Fc Receptor/Immunoglobulin G Interaction Using Antibody and Receptor Variants

Raghavan, Malini and Bonagura, Vincent R. and Morrison, Sherie L. and Bjorkman, Pamela J. (1995) Analysis of the pH Dependence of the Neonatal Fc Receptor/Immunoglobulin G Interaction Using Antibody and Receptor Variants. Biochemistry, 34 (45). pp. 14649-14657. ISSN 0006-2960. https://resolver.caltech.edu/CaltechAUTHORS:20170406-075937358

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Abstract

The neonatal Fe receptor (FcRn) binds maternal immunoglobulin G (IgG) from ingested milk in the gut (pH 6.0-6.5) and delivers it to the bloodstream of the newborn (pH 7.0-7.5). A soluble version of FcRn reproduces the physiological pH-dependent interaction with IgG, showing high-affinity binding at pH 6.0-6.5 but weak or no binding at pH 7.0-7.5. We have studied the pH dependence of the FcRn/IgG interaction using a surface plasmon resonance assay to measure kinetic and equilibrium constants. We show that the affinity of FcRn for IgG is reduced about 2 orders of magnitude as the pH is raised from 6.0 to 7.0. A Hill plot analysis suggests that several titrating residues participate in the pH-dependent affinity transition. Histidine side chains are likely candidates for residues that titrate between pH 6.0 and 7.0, and previous biochemical and structural work identified several histidines on the Fe portion of IgG that are located at the FcRn binding site. Using mutant IgG molecules and IgG subtype variants that differ in the number of histidines at the IgG/FcRn interface, we demonstrate that IgG histidines located at the junction between the CH2 and CH3 domains (residues 310 and 433) contribute to the pH-dependent affinity transition. Experiments with a mutant FcRn molecule show that two histidines on the FcRn heavy chain (residues 250 and 251) also contribute to the pH dependence of the FcRn/IgG interaction. These results are interpreted using the crystal structures of FcRn and an FcRn/Fc complex.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/bi00045a005DOIArticle
http://pubs.acs.org/doi/abs/10.1021/bi00045a005PublisherArticle
ORCID:
AuthorORCID
Bjorkman, Pamela J.0000-0002-2277-3990
Additional Information:© 1995 American Chemical Society. Received July 7, 1995; Revised Manuscript Received September 5, 1995. Supported by a Camille and Henry Dreyfuss Teacher Scholar Award (P.J.B.), the Howard Hughes Medical Institute (P.J.B.), a postdoctoral fellowship from the Cancer Research Institute (M.R.), and grants from the NIH (CA16858 and AI29470 to S.L.M.). We thank Arthur Chirino for help with using Mathematica and for making Figure IA, Dan Vaughn for suggesting the t_(1/2) calculations, and Dan Vaughn and Luis Sanchez for critical reading of the manuscript.
Funders:
Funding AgencyGrant Number
Camille and Henry Dreyfus FoundationUNSPECIFIED
Howard Hughes Medical Institute (HHMI)UNSPECIFIED
Cancer Research InstituteUNSPECIFIED
NIHCA16858
NIHAI29470
Issue or Number:45
Record Number:CaltechAUTHORS:20170406-075937358
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170406-075937358
Official Citation:Analysis of the pH Dependence of the Neonatal Fc Receptor/Immunoglobulin G Interaction Using Antibody and Receptor Variants Malini Raghavan, Vincent R. Bonagura, Sherie L. Morrison, and Pamela J. Bjorkman Biochemistry 1995 34 (45), 14649-14657 DOI: 10.1021/bi00045a005
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75779
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:06 Apr 2017 15:55
Last Modified:03 Oct 2019 16:54

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