Related topics: immune system · hiv · vaccine · protein · virus

DNA nanorobots target HER2-positive breast cancer cells

According to the Mayo Clinic, about 20% of breast cancers make abnormally high levels of a protein called human epidermal growth factor receptor 2 (HER2). When displayed on the surface of cancer cells, this signaling protein ...

Researchers discover new technique to test for viral infections

A team of Colorado State University researchers has developed technology that can detect extremely small amounts of antibodies in a person's blood. Antibodies develop to infect cells or kill pathogens, essentially fighting ...

Shrinking a medical lab to fit on a fingertip

Identifying a patient's viral infection or diagnosing a blood disorder usually requires a lab and skilled technicians. But researchers at Princeton University have developed a new technology that goes a long way toward replacing ...

Edible antibodies to treat and prevent gastrointestinal disorders

Therapeutic antibodies are increasingly being used in the clinic for the treatment of diseases. Yet, oral to gut targeting of antibodies remains a challenge due to their inability to survive digestion and reach gastrointestinal ...

From mirror-image biology to enhanced therapeutic proteins

Scientists from the German Cancer Research Center (DKFZ) have succeeded in reconstructing biomolecules in their mirror-image form. The researchers' goal is to create a mirror-image artificial protein synthesis system. Their ...

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Antibody

Antibodies (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.

This text uses material from Wikipedia, licensed under CC BY-SA