Antibodies collectively form a family of proteins known as
immunoglobulins. Each antibody molecule has a unique structure that
allows it to bind to a specific antigen, but all antibodies have a
similar overall structure.
Immunoglobulins are usually “Y” shaped and consist of two light chains and two heavy chains. The two arms of the “Y” contain the variable region, responsible for the recognition of the antigen (e.g. bacteria or virus). The stem can take one of only a limited number of forms and is known as constant region.
Each immunoglobulin molecule is made up of two heavy chains and two
light chains joined by disulfide bridges. The light and the heavy
chains are composed of constant and variable regions. Each antibody has
a variable region, which lies at the tips of the arms of the “Y”. The
variable region serves as antigen binding site. The constant region
determines isotype and hence the functional properties of the antibody.
