Chapter 34.8, Problem 1RIA

Summary Introduction

Immunoglobulins (Igs) are also termed as antibodies. Igs are glycoprotein molecules made by plasma cells (white blood cells). Igs play an important role in the immune response by particularly identifying and binding to antigens, like bacteria and viruses and thereby aids in its destruction. All Igs possess basic structure made up of four polypeptide chains, namely two identical heavy chains and two identical light chains. Both light (L) chains and heavy (H) chains encompass two different regions, such as the constant regions and the variable regions. The variable (V) regions (V_L and V_H) of an antibody possess different amino acid sequences. These regions fold together thereby forming the antigen-binding sites. The four chains are arranged in a Y with a hinge region. The stalk of the Y is known as crystallizable fragments (Fc). The top of the Y composed of two antigen-binding fragments (Fab), which attaches to compatible epitopes.