The structure of Immunoglobulin is composed of four polypeptide chains: two identical heavy chains and two identical light chains. Each chain has a variable region that recognizes and binds to a specific antigen, and a constant region that determines the class of the immunoglobulin.
The variable regions of the heavy and light chains form the antigen-binding site, which is responsible for recognizing and binding to the antigen. The antigen-binding site is highly specific, and each Immunoglobulin recognizes only one antigen or a closely related group of antigens.
The constant region of the heavy chain determines the class of the immunoglobulin, and each class has a different function and distribution in the body. The constant region also interacts with other components of the immune system, such as complement proteins and Fc receptors on white blood cells.
