IgG

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Diagram showing the five main classes of antibodies: IgG, IgA, IgD, IgE, and IgM, each with labeled light and heavy chains, disulfide bonds, and joining chains, illustrating their structural differences.

Diagram of an IgG immunoglobulin showing two heavy chains and two light chains connected by red and green dots representing intra-chain and inter-chain disulfide bonds, with labeled Fab and Fc regions and a note explaining the structure and cleavage points.

IgG

biochemistry

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June 29, 2026

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Diagram showing the five main classes of antibodies: IgG, IgA, IgD, IgE, and IgM, each with labeled light and heavy chains, disulfide bonds, and joining chains, illustrating their structural differences. — Antibody classes The five main classes of antibodies (immunoglobulins): IgG, IgA, IgD, IgE, and IgM.

IgG, or immunoglobulin G, is the most common class of immunoglobulin found in blood and tissue fluids. It is a protective protein produced by the immune system in response to foreign substances called antigens.123

Key functions of IgG include:
* Facilitating the destruction of microorganisms through phagocytosis.2
* Binding to and activating complement, a system of proteins that aids in immune response.23
* Being the only immunoglobulin capable of crossing the placenta, providing passive immunity to a developing fetus.1

IgG molecules consist of two heavy and two light protein chains, forming a Y-shape with two identical antigen-binding sites at the tips of the arms. These antibodies remain in circulation for months, offering extended immunity against specific antigens.34

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human digestive system
The gastrointestinal tract as an organ of immunity
…varieties of immunoglobulin: IgA, IgM, IgG, IgD, and IgE. B cells and plasma cells are found mainly in the cells in the spaces of the basement membrane. Another group of specialized cells are known as M cells. These are stretched over and around ordinary epithelial cells of the mucosa. The…
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…varieties of immunoglobulin: IgA, IgM, IgG, IgD, and IgE. B cells and plasma cells are found mainly in the cells in the spaces of the basement membrane. Another group of specialized cells are known as M cells. These are stretched over and around ordinary epithelial cells of the mucosa. The…
Read More

immune system disorder
Rheumatoid arthritis
…tail region of the Y-shaped IgG molecule—in other words, rheumatoid factor is anti-IgG antibodies. Immune complexes form between rheumatoid factor and IgG and apparently are deposited in the synovial membrane of joints. The deposition triggers a type III hypersensitivity reaction, activating complement and attracting granulocytes, which causes inflammation and pain…
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…tail region of the Y-shaped IgG molecule—in other words, rheumatoid factor is anti-IgG antibodies. Immune complexes form between rheumatoid factor and IgG and apparently are deposited in the synovial membrane of joints. The deposition triggers a type III hypersensitivity reaction, activating complement and attracting granulocytes, which causes inflammation and pain…
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immune system
Passive immunization
Protective immunoglobulins—primarily of the IgG class—can be prepared from the blood of humans or other species (e.g., horses or rabbits) that have already developed specific immunity against the relevant antigens. These preparations are known as antiserums. (This explains the original term for passive immunization, which is serum therapy.) Human…
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Protective immunoglobulins—primarily of the IgG class—can be prepared from the blood of humans or other species (e.g., horses or rabbits) that have already developed specific immunity against the relevant antigens. These preparations are known as antiserums. (This explains the original term for passive immunization, which is serum therapy.) Human…
Read More