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===Antigen Binding Site=== | ===Antigen Binding Site=== | ||
[[Image:B cell diagram.jpg| 250 px| thumb|right|'''Figure 1.''' Overview of the human B Cell Receptor and its structural components. Used with permission under Wikimedia Commons.]] | [[Image:B cell diagram.jpg| 250 px| thumb|right|'''Figure 1.''' Overview of the human B Cell Receptor and its structural components. Used with permission under Wikimedia Commons.]] | ||
| - | The binding of an antigen to the human B Cell receptor is identical to other common soluble antibodies (such as [https://en.wikipedia.org/wiki/Immunoglobulin_G IgG], [https://en.wikipedia.org/wiki/Immunoglobulin_A IgA], [https://en.wikipedia.org/wiki/Immunoglobulin_M IgM], [https://en.wikipedia.org/wiki/Immunoglobulin_E IgE], or [https://en.wikipedia.org/wiki/Immunoglobulin_D IgD]). The antibody portion of the B Cell Receptor is roughly "Y" shaped and consists of two identical <scene name='95/952701/Heavy_chains_highlight/2'>heavy</scene> and two identical <scene name='95/952701/Light_chains_highlight/3'>light</scene> chains creating two similar epitope or binding regions<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. Thus, two antigen molecules can bind independent of one another to produce a response. Within this structure, there are both constant and variable regions. The stem of the "Y" is a <scene name='95/952701/Constant_stem/1'>constant region</scene> ([https://en.wikipedia.org/wiki/Antibody#CDRs,_Fv,_Fab_and_Fc_Regions Fc]) composed of only heavy chain interactions<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. The two heavy chains then branch at a flexible <scene name='95/952701/Hinge/1'>hinge region</scene>. These interact individually with one light chain creating two [https://en.wikipedia.org/wiki/Antibody#CDRs,_Fv,_Fab_and_Fc_Regions Fab] fragments or branches of the "Y"<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. Each <scene name='95/952701/Fab/1'>Fab fragment</scene> additionally contains a <scene name='95/952701/Fv_region/1'>variable region</scene> ([https://en.wikipedia.org/wiki/Antibody#CDRs,_Fv,_Fab_and_Fc_Regions Fv]) and a <scene name='95/952701/Fab_constant/1'>constant region</scene><Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. The variable region sits on top of the constant region and consists of hyper-variable loops which are random coils of amino acids that are unique to an antibody and exposed to allow specific recognition of an antigen<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. Furthermore, the light chains interact with the heavy chains via weak intermolecular forces and disulfide bridges<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. Therefore, binding to an antigen is processed through intermolecular interactions and is specific due to unique hyper variable loop sequences. | + | The binding of an antigen to the human B Cell receptor is identical to other common soluble antibodies (such as [https://en.wikipedia.org/wiki/Immunoglobulin_G IgG], [https://en.wikipedia.org/wiki/Immunoglobulin_A IgA], [https://en.wikipedia.org/wiki/Immunoglobulin_M IgM], [https://en.wikipedia.org/wiki/Immunoglobulin_E IgE], or [https://en.wikipedia.org/wiki/Immunoglobulin_D IgD]). The antibody portion of the B Cell Receptor is roughly "Y" shaped and consists of two identical <scene name='95/952701/Heavy_chains_highlight/2'>heavy</scene> and two identical <scene name='95/952701/Light_chains_highlight/3'>light</scene> chains creating two similar epitope or binding regions<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref> (figure 1). Thus, two antigen molecules can bind independent of one another to produce a response. Within this structure, there are both constant and variable regions. The stem of the "Y" is a <scene name='95/952701/Constant_stem/1'>constant region</scene> ([https://en.wikipedia.org/wiki/Antibody#CDRs,_Fv,_Fab_and_Fc_Regions Fc]) composed of only heavy chain interactions<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. The two heavy chains then branch at a flexible <scene name='95/952701/Hinge/1'>hinge region</scene>. These interact individually with one light chain creating two [https://en.wikipedia.org/wiki/Antibody#CDRs,_Fv,_Fab_and_Fc_Regions Fab] fragments or branches of the "Y"<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. Each <scene name='95/952701/Fab/1'>Fab fragment</scene> additionally contains a <scene name='95/952701/Fv_region/1'>variable region</scene> ([https://en.wikipedia.org/wiki/Antibody#CDRs,_Fv,_Fab_and_Fc_Regions Fv]) and a <scene name='95/952701/Fab_constant/1'>constant region</scene><Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. The variable region sits on top of the constant region and consists of hyper-variable loops which are random coils of amino acids that are unique to an antibody and exposed to allow specific recognition of an antigen<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. Furthermore, the light chains interact with the heavy chains via weak intermolecular forces and disulfide bridges<Ref name="Janeway CA">Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001. </Ref>. Therefore, binding to an antigen is processed through intermolecular interactions and is specific due to unique hyper variable loop sequences. |
===Heavy Chain Interactions (Iga and IgB)=== | ===Heavy Chain Interactions (Iga and IgB)=== | ||
Revision as of 17:22, 10 April 2023
Contents |
H. sapiens mIgM B Cell Receptor
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Medical Relevancy
Janeway CA Jr, Travers P, Walport M, et al. Immunobiology: The Immune System in Health and Disease. 5th edition. New York: Garland Science; 2001.
Disease
B-cells and their respective receptors play an important role in the immune response. Therefore, if the receptors were to not function properly, there would be damaging consequences. Autoimmune disease is suggested to occur when somatic cells are recognized as foreign antigens and the body tries to eliminate them. Although the exact mechanism of disease has not been provided, it is thought that B-cell receptors are an essential part of these diseases due to their function and role in the immune systems. B-cell receptors are improperly recognizing somatic cells from different tissues depending on the disease and elicit the production of antibodies against them (autoantibodies). This causes destruction of these cell types. Examples of these diseases include rheumatoid arthritis where the lining of joints is targeted and degraded, multiple sclerosis which targets the myelin sheath that surrounds nerve cells, type 1 diabetes mellitus where the insulin producing cells are targeted for destruction, and systematic lupus erythematosus where multiple organ systems are targeted (skin, brain, lungs, and kidneys are common targets).
