5LG1

Room temperature structure of human IgG4-Fc from crystals analysed in situ

Summary for 5LG1

• Entry DOI: 10.2210/pdb5lg1/pdb
• Descriptor: Ig gamma-4 chain C region, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-2)-alpha-D-mannopyranose-(1-3)-[2-acetamido-2-deoxy-beta-D-glucopyranose-(1-2)-alpha-D-mannopyranose-(1-6)]beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[alpha-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranose (3 entities in total)
• Functional Keywords: antibody immunoglobulin, immune system
• Biological source: Homo sapiens (Human)
• Cellular location: Secreted : P01861
• Total number of polymer chains: 2
• Total formula weight: 51423.32

Authors

Davies, A.M.,Rispens, T.,Ooijevaar-de Heer, P.,Aalberse, R.C.,Sutton, B.J. (deposition date: 2016-07-05, release date: 2016-12-14, Last modification date: 2024-10-23)

Primary citation

Davies, A.M.,Rispens, T.,Ooijevaar-de Heer, P.,Aalberse, R.C.,Sutton, B.J.
Room temperature structure of human IgG4-Fc from crystals analysed in situ.
Mol. Immunol., 81:85-91, 2016

PubMed Abstract: The Fc region of IgG antibodies (Cγ2 and Cγ3 domains) is responsible for effector functions such as antibody-dependent cell-mediated cytotoxicity and phagocytosis, through engagement with Fcγ receptors, although the ability to elicit these functions differs between the four human IgG subclasses. A key determinant of Fcγ receptor interactions is the FG loop in the Cγ2 domain. High resolution cryogenic IgG4-Fc crystal structures have revealed a unique conformation for this loop, which could contribute to the particular biological properties of this subclass. To further explore the conformation of the IgG4 Cγ2 FG loop at near-physiological temperature, we solved a 2.7Å resolution room temperature structure of recombinant human IgG4-Fc from crystals analysed in situ. The Cγ2 FG loop in one chain differs from the cryogenic structure, and adopts the conserved conformation found in IgG1-Fc; however, this conformation participates in extensive crystal packing interactions. On the other hand, at room temperature, and free from any crystal packing interactions, the Cγ2 FG loop in the other chain adopts the conformation previously observed in the cryogenic IgG4-Fc structures, despite both conformations being accessible. The room temperature human IgG4-Fc structure thus provides a more complete and physiologically relevant description of the conformation of this functionally critical Cγ2 FG loop.

PubMed: 27915153
DOI: 10.1016/j.molimm.2016.11.021

Experimental method

X-RAY DIFFRACTION (2.7 Å)