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Published May 2004 | Supplemental Material
Journal Article Open

The Chicken Yolk Sac IgY Receptor, a Functional Equivalent of the Mammalian MHC-Related Fc Receptor, Is a Phospholipase A_2 Receptor Homolog

Abstract

In mammals, IgG is transferred from mother to young by the MHC-related receptor FcRn, which binds IgG in acidic endosomes and releases it at basic pH into blood. Maternal IgY, the avian counterpart of IgG, is transferred to embryos across yolk sac membranes. We affinity-purified the chicken yolk sac IgY receptor (FcRY) and sequenced its gene. FcRY is unrelated to MHC molecules but is a homolog of the mammalian phospholipase A_2 receptor. Analytical ultracentrifugation and truncation experiments suggest that FcRY forms a compact structure containing an IgY binding site at acidic pH but undergoes a conformational change at basic pH that disrupts the site. FcRY is thus unrelated to mammalian FcRn in both its structure and mechanism for pH-dependent binding, illustrating distinct routes utilized by evolution to transfer antibodies.

Additional Information

© 2004 Cell Press. Received 1 January 2004, Revised 1 March 2004, Accepted 17 March 2004, Available online 18 May 2004Published: May 18, 2004. We thank Gary M. Hathaway from the Caltech protein and peptide microanalysis facility for performing the protein microsequencing, digestion, peptide HPLC, and mass spectroscopy; Peter Snow of the Caltech Protein Expression Center for baculovirus expression of FcRY; Marianne Bronner-Fraser for providing fertilized chicken eggs; Marta Murphy for cover artwork; and members of the Bjorkman laboratory for critical reading of the manuscript. This work was supported by the Cancer Research Fund of the Damon-Runyon Walter Winchell Foundation (DRG-1445 to A.P.W. and DRG-1658 to A.B.H.), a career research award from the Burroughs-Wellcome Fund (A.P.W.), the NIH (2 R01 AI041239-06A1 to P.J.B.), and the Howard Hughes Medical Institute (P.J.B.). Accession Numbers: The FcRY cDNA sequence has been deposited in GenBank with accession number AY450642.

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Created:
August 19, 2023
Modified:
October 25, 2023