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Immunoglobulin M (IgM) is the largest of several isotypes of antibodies (also known as immunoglobulin) that are produced by vertebrates. IgM is the first antibody to appear in the response to initial exposure to an antigen ; [ 1 ] [ 2 ] causing it to also be called an acute phase antibody.
[2] [16] Among the many functions of C1q, C1q triggers clearance of immune complexes and apoptotic cells by activating the classical pathway and binding directly onto phagocytes. [ 1 ] [ 17 ] Consequently, systemic lupus erythematosus from insufficient amounts of C1q is characterized by the accumulation of autoantibodies and apoptotic cells. [ 4 ]
The J chain is a glycoprotein of molecular weight 15 kDa. Its secondary structure remains undetermined but is believed to adopt either a single β-barrel or two-domain folded structure with standard immunoglobulin domains. [10] The J chain's primary structure is unusually acidic having a high content of negatively charged amino acids. [11]
The pentameric structure of IgM antibodies makes them efficient at binding antigens with repetitive epitopes (e.g. bacterial capsule, viral capsid) and activation of complement cascade. As IgM antibodies are expressed early in a B cell response, they are rarely highly mutated and have broad antigen reactivity thus providing an early response to ...
Antibody (or immunoglobulin) structure is made up of two heavy-chains and two light-chains. These chains are held together by disulfide bonds. The arrangement or processes that put together different parts of this antibody molecule play important role in antibody diversity and production of different subclasses or classes of antibodies.
The antibodies IgM or certain subclasses of IgG complexed with antigens are able to initiate the complement system: a single pentameric IgM can initiate the pathway, while several monomeric IgG molecules are needed. [3]
Each heavy chain has two regions: a constant region (which is the same for all immunoglobulins of the same class but differs between classes).. Heavy chains γ, α and δ have a constant region composed of three tandem (in a line next to each other) immunoglobulin domains but also have a hinge region for added flexibility.
Hydrogen bond interactions will induce the enzymatic activity of an enzyme; therefore, the more hydrogen bonds that are present at the antibody-antigen binding site will result in a stronger, more stable binding structure. [1] The tertiary structure of an antibody is important to analyze and design new antibodies. The structure and sequence of ...