IgG binding

Definition

Target type: molecularfunction

Binding to an immunoglobulin of an IgG isotype. [GOC:add, ISBN:0781735149]

IgG binding is a crucial molecular interaction in the immune system, mediated by antibodies, specifically immunoglobulin G (IgG). These antibodies are Y-shaped proteins with two identical antigen-binding sites located at the tips of the arms. Each arm consists of a variable region, responsible for recognizing and binding specific epitopes (antigenic determinants) on the surface of pathogens or other antigens.

The interaction between IgG and its target antigen involves a complex interplay of non-covalent forces, including hydrogen bonding, electrostatic interactions, van der Waals forces, and hydrophobic interactions. These forces work together to establish a high-affinity and specific interaction between the antibody and its antigen.

IgG binding plays a critical role in various immune functions, including:

1. **Neutralization:** IgG antibodies can neutralize pathogens by blocking their ability to bind to and infect host cells. This is achieved by binding to the pathogen's surface proteins or other molecules that are essential for its infectivity.

2. **Opsonization:** IgG antibodies can coat pathogens, making them more susceptible to phagocytosis by immune cells like macrophages and neutrophils. This process is known as opsonization and enhances the efficiency of pathogen clearance.

3. **Complement activation:** The binding of IgG to an antigen can activate the complement system, a cascade of proteins that can lead to the lysis of pathogens, the recruitment of immune cells, and the enhancement of inflammation.

4. **Antibody-dependent cell-mediated cytotoxicity (ADCC):** IgG antibodies can bind to target cells, such as cancer cells or infected cells, and trigger their destruction by natural killer (NK) cells. NK cells recognize the IgG bound to the target cell and release cytotoxic molecules that induce cell death.

5. **Immune complex formation:** IgG antibodies can bind to soluble antigens, forming immune complexes that can activate various immune responses, including complement activation and phagocytosis.

In summary, IgG binding is a multifaceted molecular interaction that is essential for the proper functioning of the adaptive immune system. It plays a crucial role in neutralizing pathogens, enhancing phagocytosis, activating the complement system, triggering ADCC, and forming immune complexes, all of which contribute to the elimination of threats and the maintenance of immune homeostasis.'
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Proteins (1)

Compounds (2)