Is an antigen a protein

Antigens are usually proteins, peptides (amino acid chains) and polysaccharides (chains of monosaccharides/simple sugars) but lipids and nucleic acids become antigens only when combined with proteins and polysaccharides.

What is a specific protein that attaches itself to an antigen?

On the surface of a B cell is a B cell receptor (BCR) protein. The BCR enables B cells to capture and bind to an antigen. Once bound, the antigen is internalized and digested by the B cell and certain molecules from the antigen are attached to another protein called a class II MHC protein .

What is protein made in response to a specific antigen?

Antibody , also called immunoglobulin, a protective protein produced by the immune system in response to the presence of a foreign substance, called an antigen. Antibodies recognize and latch onto antigens in order to remove them from the body.

How can an antibody recognize an antigen?

Antibodies recognize specific antigens by identifying certain areas on the surface of the antigen known as antigenic determinants. Once the specific antigenic determinant is recognized, the antibody will bind to the determinant. The antigen is tagged as an intruder and labeled for destruction by other immune cells.

What is the relationship between an antigen and an antibody?

The main difference between antigen and antibody is that an antigen is a substance that can trigger an immune response in the body whereas n antibody is the globin protein produced in response to a specific antigen. In order to elicit an immune response, an antigen should bind to an antibody or T-cell receptor.

What is a specific antibody?

A specific antibody is added, and binds to antigen (hence the ‘sandwich’: the antigen is stuck between two antibodies). This primary antibody could also be in the serum of a donor to be tested for reactivity towards the antigen.

What is the difference between antigen and hapten?

At the molecular level, an antigen can be characterized by its ability to bind to an antibody’s variable Fab region. Different antibodies have the potential to discriminate among specific epitopes present on the antigen surface. A hapten is a small molecule that changes the structure of an antigenic epitope.

Is a hapten an incomplete antigen?

A hapten is essentially an incomplete antigen. These small molecules can elicit an immune response only when attached to a large carrier such as a protein; the carrier typically does not elicit an immune response by itself.

What are the surface features of an antigen?

Epitope – The distinct surface features of an antigen, its antigenic determinant. Antigenic molecules, normally “large” biological polymers, usually present surface features that can act as points of interaction for specific antibodies. Any such feature constitutes an epitope.