Structure of Antibody Molecule (With Diagram)

In this article we will discuss about the structure of an antibody molecule with the help of a suitable diagram. Also learn about its types.

Antibody is a type of protein molecule produced by B-lymphocytes in response to pathogens. T-cells do not secrete antibodies directly however, they help B-cells to produce them. Each antibody molecule has four peptide chains.

Out of the four chains are:

(i) Two small chains called Light (L) chains.

(ii) Two large chains called Heavy (H) chains.

An antibody is represented as H₂L₂ molecule. In our body, different types of antibodies are produced such as IgA, IgM, IgE, IgG.

Response via antibodies is also called as humoral immune response. These antibodies are found in blood.

Type of Antibodies:

IgG:

1. Most Prevent class of antibody 75-80% of total antibody.

2. Protects against fungi , bacteria, toxins, etc.

3. It can cross placenta from mother to child and provides immune protection to new born.

4. Responsible for RH factors in blood.

IgM:

1. Third most common antibody. Constitutes 5-10% of total antibodies.

2. They are first to be produced in responses to encounter with a pathogen.

3. Responsible for blood transfusion reaction in ABO blood system.

IgA:

1. Second most prevent antibody.

2. It is 15% of the total antibodies.

3. Secreted through parts lined by mucous system.

4. Found in secretions from nose, eyes , lungs and digestive tract , saliva , tears ,etc.

5. Also found in colostrum i.e breasts milk for newborns immune protection.

IgE:

1. The least common antibody.

2. It make up to only 0.002% of total antibodies and is involved in allergic reactions.

3. It is 0.2% of antibodies in the body.

IgD:

1. Their function is not well understood yet.