ArticleProceedings of the National Academy of Sciences of the United States of America2009
The human IgM pentamer is a mushroom-shaped molecule with a flexural bias.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 98 papers.
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Who cites it
98 citing papers in PubMed, 200 citations in OpenAlex.
- Label-Free Profiling of Immunoglobulin Isotypes Using Solid-State Nanopores.Small methods · 2026Article
- Reconstruction of the Flexible IgM Fc Core Using Atomic Force Microscopy Topography and the AFM-Assembly Pipeline.Journal of molecular recognition : JMR · 2026Article
- IgM-C4d Complex Causes the Inaccurate Measurement of Serum Uric Acid Levels via the Uricase Method.Current issues in molecular biology · 2026Article
- Electroosmotic Flow-Driven Nanopore Translocation of Large, Conformationally Dynamic Proteins: Overcoming Steric and Electrostatic Barriers.Journal of the American Chemical Society · 2026Article
- Defining the Features of Complement-Active IgM.Journal of molecular biology · 2025Article
- Enteroviruses Activate Cellular Innate Immune Responses Prior to Adaptive Immunity and Tropism Contributes to Severe Viral Pathogenesis.Microorganisms · 2025Review
- Harnessing IgM for solid tumor therapy: biology, engineering advances, and translational challenges.Frontiers in immunology · 2025Review
- Different antibody isotypes against tuberculosis: what we know and what we need to know.Frontiers in immunology · 2025Review
- Intestinal immunoglobulins under microbial dysbiosis: implications in opioid-induced microbial dysbiosis.Frontiers in microbiology · 2025Review
- Gut microbial dysbiosis activates the classical complement pathway in a short-term morphine treatment model.Gut microbes reports · 2025Article
- Anionic lipids direct efficient microfluidic encapsulation of stable and functionally active proteins in lipid nanoparticles.Communications materials · 2025Article
- Targeting the epidermal growth factor receptor using IgM antibodies: toward next generation cancer immunotherapy.Frontiers in immunology · 2025Article
- Some Human Anti-Glycan Antibodies Lack the Ability to Activate the Complement System.Antibodies (Basel, Switzerland) · 2024Article
- Complement Activation Is Associated With Disease Severity in Multiple Sclerosis.Neurology(R) neuroimmunology & neuroinflammation · 2024Article
- Assessing the Affinity Spectrum of the Antigen-Specific B Cell Repertoire via ImmunoSpotMethods in molecular biology (Clifton, N.J.) · 2024Article
- Cloaking antibodies are prevalent inFrontiers in cellular and infection microbiology · 2024Article
- Cryo-electron microscopy of IgM-VAR2CSA complex reveals IgM inhibits binding of Plasmodium falciparum to Chondroitin Sulfate A.Nature communications · 2023Article
- Immunoglobulin adsorption and film formation on mechanically wrinkled and crumpled surfaces at submonolayer coverage.Nanoscale advances · 2023Article
- Targeted delivery of harmine to xenografted human pancreatic islets promotes robust cell proliferation.Scientific reports · 2022Article
- IgM antibodies derived from memory B cells are potent cross-variant neutralizers of SARS-CoV-2.The Journal of experimental medicine · 2022Article
38 more citing papers are in PubMed but not listed here.
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Authors and funding
2 authors at 2 institutions in 2 countries.
Funding
Abstract
The textbook planar model of pentameric IgM, a potent activator of complement C1q, is based upon the crystallographic structure of IgG. Although widely accepted, key predictions of this model have not yet been directly confirmed, which is particularly important since IgG lacks a major Ig fold domain in its Fc region that is present in IgM. Here, we construct a homology-based structural model of the IgM pentamer using the recently obtained crystallographic structure of IgE Fc, which has this additional Ig domain, under the constraint that all of the cysteine residues known to form disulfide bridges both within each monomer and between monomers are bonded together. In contrast to the planar model, this model predicts a non-planar, mushroom-shaped complex, with the central portion formed by the C-terminal domains protruding out of the plane formed by the Fab domains. This unexpected conformation of IgM is, however, directly confirmed by cryo-atomic force microscopy of individual human IgM molecules. Further analysis of this model with free energy calculations of out-of-plane Fab domain rotations reveals a pronounced asymmetry favoring flexions toward the central protrusion. This bias, together with polyvalent attachment to cell surface antigen, would ensure that the IgM pentamer is oriented on the cell membrane with its C1q binding sites fully exposed to the solution, and thus provides a mechanistic explanation for the first steps of C1q activation by IgM.
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