Antibody
hideAntibodies (also known as immunoglobulins, abbreviated Ig) are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. They are typically made of basic structural units—each with two large heavy chains and two small light chains—to form, for example, monomers with one unit, dimers with two units or pentamers with five units. Antibodies are produced by a kind of white blood cell called a plasma cell. There are several different types of antibody heavy chains, and several different kinds of antibodies, which are grouped into different isotypes based on which heavy chain they possess. Five different antibody isotypes are known in mammals, which perform different roles, and help direct the appropriate immune response for each different type of foreign object they encounter.
Although the general structure of all antibodies is very similar, a small region at the tip of the protein is extremely variable, allowing millions of antibodies with slightly different tip structures, or antigen binding sites, to exist. This region is known as the hypervariable region. Each of these variants can bind to a different target, known as an antigen. This huge diversity of antibodies allows the immune system to recognize an equally wide diversity of antigens. The unique part of the antigen recognized by an antibody is called an epitope. These epitopes bind with their antibody in a highly specific interaction, called induced fit, that allows antibodies to identify and bind only their unique antigen in the midst of the millions of different molecules that make up an organism. Recognition of an antigen by an antibody tags it for attack by other parts of the immune system. Antibodies can also neutralize targets directly by, for example, binding to a part of a pathogen that it needs to cause an infection.
The large and diverse population of antibodies is generated by random combinations of a set of gene segments that encode different antigen binding sites (or paratopes), followed by random mutations in this area of the antibody gene, which create further diversity. Antibody genes also re-organize in a process called class switching that changes the base of the heavy chain to another, creating a different isotype of the antibody that retains the antigen specific variable region. This allows a single antibody to be used by several different parts of the immune system. Production of antibodies is the main function of the humoral immune system.
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News tagged with antibodies
Researchers discover antibody receptor identity, propose renaming immune-system gene
Nov 20, 2009 |
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Researchers at the University of Alabama at Birmingham (UAB) have uncovered the genetic identity of a cellular receptor for the immune system's first-response antibody, a discovery that sheds new light on ...
Scientists identify DNA that regulates antibody production
Nov 20, 2009 |
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(PhysOrg.com) -- When foreign invaders trip the immune system’s alarm, antibodies need to be specially sculpted to attack them head on. New research now shows that gene segments called enhancers control the reshuffling of ...
Vaccine being developed to help smokers quit
Medicine & Health / Medications
Nov 20, 2009 |
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(PhysOrg.com) -- Glaxo-SmithKline has joined forces with Nabi Pharmaceuticals to produce a vaccine to help smokers give up their addiction permanently.
New findings suggest strategy to help generate HIV-neutralizing antibodies
Medicine & Health / HIV & AIDS
Nov 19, 2009 |
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New discoveries about anti-HIV antibodies may bring researchers a step closer to creating an effective HIV vaccine, according to a new paper co-authored by scientists at the Vaccine Research Center of the National Institute ...
Scientists explain binding action of 2 key HIV antibodies; could lead to new vaccine design
Nov 09, 2009 |
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A very close and detailed study of how the most robust antibodies work to block the HIV virus as it seeks entry into healthy cells has revealed a new direction for researchers hoping to design an effective vaccine.
Researchers pioneer kidney disease prediction method
Nov 05, 2009 |
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(PhysOrg.com) -- A study into the relationship between antibodies and proteins in people with Lupus could mean earlier diagnosis of kidney disease in such patients, and lead the way for earlier diagnoses for ...
New Synthetic Molecules Trigger Immune Response to HIV and Prostate Cancer
Nov 05, 2009 |
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(PhysOrg.com) -- Researchers at Yale University have developed synthetic molecules capable of enhancing the body’s immune response to HIV and HIV-infected cells, as well as to prostate cancer cells. Their ...
Early-stage, HER2-positive breast cancer patients at increased risk of recurrence
Nov 02, 2009 |
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Early-stage breast cancer patients with HER2 positive tumors one centimeter or smaller are at significant risk of recurrence of their disease, compared to those with early-stage disease who do not express the aggressive protein, ...
Breakthrough in fight against Hendra virus
Oct 30, 2009 |
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(PhysOrg.com) -- There has been a breakthrough in the fight against the deadly Hendra virus following the development of a treatment which shows great potential to save the lives of people who become infected ...
Scientists Propose New Explanation for Flu Virus Antigenic Drift
Oct 29, 2009 |
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(PhysOrg.com) -- Influenza viruses evade infection-fighting antibodies by constantly changing the shape of their major surface protein. This shape-shifting, called antigenic drift, is why influenza vaccines ...
Vegetables can protect unborn child against diabetes
Oct 27, 2009 |
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New evidence is emerging for how important it is for pregnant women to eat good, nutritious food. Expecting mothers who eat vegetables every day seem to have children who are less likely to develop type 1 diabetes, is revealed ...
Rethinking the antibody-dependent enhancement dengue hemorrhagic fever model
Oct 26, 2009 |
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Research published this week in PLoS Medicine challenges the dogma of the antibody-dependent enhancement model (ADE) for the development of dengue hemorrhagic fever (DHF).
Scientists discover promising new path for treating traumas
Oct 25, 2009 |
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(PhysOrg.com) -- A discovery by scientists at the Oklahoma Medical Research Foundation could help save lives threatened by traumatic injuries like those sustained in car crashes or on the battlefield. The ...
Is duodenal biopsy necessary in celiac disease diagnosis for children and adults?
Oct 23, 2009 |
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Duodenal biopsy remains the gold standard for celiac disease (CD) diagnosis. However, it has several pitfalls and requires an invasive procedure in children. In the past few years, a more prominent role for a definitive diagnosis ...
Cocaine Vaccine Shows Promise for Treating Addiction
Oct 05, 2009 |
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(PhysOrg.com) -- Immunization with an experimental anti-cocaine vaccine resulted in a substantial reduction in cocaine use in 38 percent of vaccinated patients in a clinical trial supported by the National Institute on Drug ...
