The role of the Immunoglobulin G1 Fc N-glycan in FcγRIIIa affinity

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2014-01-01
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Hanson, Quinlin
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Adam Barb
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Biochemistry, Biophysics and Molecular Biology

The Department of Biochemistry, Biophysics, and Molecular Biology was founded to give students an understanding of life principles through the understanding of chemical and physical principles. Among these principles are frontiers of biotechnology such as metabolic networking, the structure of hormones and proteins, genomics, and the like.

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The Department of Biochemistry and Biophysics was founded in 1959, and was administered by the College of Sciences and Humanities (later, College of Liberal Arts & Sciences). In 1979 it became co-administered by the Department of Agriculture (later, College of Agriculture and Life Sciences). In 1998 its name changed to the Department of Biochemistry, Biophysics, and Molecular Biology.

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1959–present

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  • Department of Biochemistry and Biophysics (1959–1998)

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Biochemistry, Biophysics and Molecular Biology
Abstract

IgG1 Fc is a remarkable molecule, capable of initiating pro-inflammatory or anti-inflammatory responses by binding to Fc receptors. IgG1 Fc has a conserved glycosylation site at N297. The presence of the carbohydrate at N297 is vital for proper Fc function. Intramolecular glycan-polypeptide interactions are thought to impose conformational restrictions on Fc that maintain binding-favorable interactions. Perturbations of these intramolecular interactions may result in disrupted binding of Fc. In this work, we mutate residues at the glycan-polypeptide interface to disrupt the contacts between the glycan and polypeptide. Using MALDI-TOFMS and SPR we demonstrate that Fc mutants display more highly processed glycans and reduced affinity for FcγRIIIa. Furthermore, we mutate residues at the interface of the Cγ2 and Cγ3 domains that do not have highly processed glycans, but still have impaired binding to FcγRIIIa. Finally, we conclude with a mIgG2a Fc protein construct that shows promise for testing Fc functionality in cellular systems.

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Wed Jan 01 00:00:00 UTC 2014