Structure and Functions of Immunoglobulins (Antibodies)
The Organization of Heavy and Light Chains in an Immunoglobulin (Ig)
In the previous post, we have discussed the introductory features of antibodies. There we have also discussed the reason for calling Antibodies (Ab) as Immunoglobulins (Ig). In this lesson, we will see the detailed molecular structure and organization of immunoglobulins (antibodies).
What are Immunoglobulins (Ig)?
As we discussed earlier, the Antibodies or Immunoglobulins are globular proteins present in the serum and tissue fluids. They are produced by the plasma cells (B-cells) and are used in the immune system of the body to neutralize pathogenic microbes or other toxic foreign components. Antibodies play a very crucial role in the immune system of an organism. Antibodies bind to definite molecules of microbes called antigens with high affinity and specificity. This enables our immune system to detect foreign organisms such as invading pathogens, of its products and initiate the mechanism to eliminate these foreign particles. The production of antibodies by the plasma cells is also stimulated by the antigens.
How Immunoglobulins (Ig) are classified?
The immunoglobulins constitute about 20 – 25% of the total serum proteins. Based on the Physiochemical and Antigenic differences, the immunoglobulins are classified into FIVE categories. These immunoglobulins variants are called as Isotypes. The five isotypes or classes of the immunoglobulins are given below.