3ay4 | pdb_00003ay4
Crystal structure of nonfucosylated Fc complexed with bis-glycosylated soluble form of Fc gamma receptor IIIa
Structural highlights
Disease[IGHG1_HUMAN] Defects in IGHG1 are a cause of multiple myeloma (MM) [MIM:254500]. MM is a malignant tumor of plasma cells usually arising in the bone marrow and characterized by diffuse involvement of the skeletal system, hyperglobulinemia, Bence-Jones proteinuria and anemia. Complications of multiple myeloma are bone pain, hypercalcemia, renal failure and spinal cord compression. The aberrant antibodies that are produced lead to impaired humoral immunity and patients have a high prevalence of infection. Amyloidosis may develop in some patients. Multiple myeloma is part of a spectrum of diseases ranging from monoclonal gammopathy of unknown significance (MGUS) to plasma cell leukemia. Note=A chromosomal aberration involving IGHG1 is found in multiple myeloma. Translocation t(11;14)(q13;q32) with the IgH locus. Translocation t(11;14)(q13;q32) with CCND1; translocation t(4;14)(p16.3;q32.3) with FGFR3; translocation t(6;14)(p25;q32) with IRF4. [FCG3A_HUMAN] The disease is caused by mutations affecting the gene represented in this entry.[1] [2] [3] [4] Function[FCG3A_HUMAN] Receptor for the Fc region of IgG. Binds complexed or aggregated IgG and also monomeric IgG. Mediates antibody-dependent cellular cytotoxicity (ADCC) and other antibody-dependent responses, such as phagocytosis.[5] [6] Publication Abstract from PubMedRemoval of the fucose residue from the N-glycans of the Fc portion of immunoglobulin G (IgG) results in a dramatic enhancement of antibody-dependent cellular cytotoxicity (ADCC) through improved affinity for Fcgamma receptor IIIa (FcgammaRIIIa). Here, we present the 2.2-A structure of the complex formed between nonfucosylated IgG1-Fc and a soluble form of FcgammaRIIIa (sFcgammaRIIIa) with two N-glycosylation sites. The crystal structure shows that one of the two N-glycans of sFcgammaRIIIa mediates the interaction with nonfucosylated Fc, thereby stabilizing the complex. However, fucosylation of the Fc N-glycans inhibits this interaction, because of steric hindrance, and furthermore, negatively affects the dynamics of the receptor binding site. Our results offer a structural basis for improvement in ADCC of therapeutic antibodies by defucosylation. Structural basis for improved efficacy of therapeutic antibodies on defucosylation of their Fc glycans.,Mizushima T, Yagi H, Takemoto E, Shibata-Koyama M, Isoda Y, Iida S, Masuda K, Satoh M, Kato K Genes Cells. 2011 Nov;16(11):1071-1080. doi:, 10.1111/j.1365-2443.2011.01552.x. PMID:22023369[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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