Question

Describe the structure of an antibody.

Answer 1

Antibody:

1. The antibody is a protein made by plasma cells in response to an antigen.

Structure of an antibody:

1. Each antibody consists of four polypeptides, which are two light chains and two heavy chains.
2. The light and heavy chains join to form a Y-shaped structure.
3. The amino acid sequence at the tip of the Y-structure varies among different antibodies and is known as the variable region.
4. The variable region is composed of $110$to $130$ amino acids.
5. The variable region is antigen-specific and is divided into hypervariable (HV) and framework (FR) regions.
6. The other region is the constant region according to which antibodies can be classified as IgM, IgG, IgA, IgD, and IgE