Immunoglobulin light chain

Component of an antibody

Diagram of antibody chains

Immunoglobulin light chains are integral components of antibodies, which are also known as immunoglobulins. These light chains are part of the structure of antibodies and play a crucial role in the immune response by binding to antigens. Each antibody is composed of two identical heavy chains and two identical light chains, forming a Y-shaped structure.

Structure

Structure of IgG2 antibody

Immunoglobulin light chains are polypeptide chains that are approximately 211 to 217 amino acids in length. They are classified into two types: kappa (κ) and lambda (λ) light chains. Each antibody contains either kappa or lambda light chains, but not both. The light chains are connected to the heavy chains via disulfide bonds, contributing to the stability and specificity of the antibody.

The light chain consists of two domains: the variable (V) domain and the constant (C) domain. The variable domain is responsible for antigen binding and varies greatly among different antibodies, allowing for the diversity of the immune response. The constant domain is more conserved and plays a role in the structural integrity of the antibody.

Function

The primary function of immunoglobulin light chains is to contribute to the antigen-binding site of the antibody. The variable region of the light chain pairs with the variable region of the heavy chain to form the antigen-binding site, which is highly specific to particular antigens. This specificity is crucial for the immune system to recognize and neutralize pathogens effectively.

Light chains also play a role in the overall stability and solubility of the antibody molecule. They help maintain the proper conformation of the antibody, which is essential for its function in the immune response.

Clinical Significance

Abnormal production of immunoglobulin light chains can lead to various medical conditions. For instance, in multiple myeloma, a type of blood cancer, there is an overproduction of a single type of light chain, which can be detected in the blood and urine. These free light chains, known as Bence Jones proteins, can cause kidney damage and other complications.

Light chain amyloidosis is another condition associated with abnormal light chain production, where misfolded light chains deposit in tissues, leading to organ dysfunction.

Related pages

• Antibody
• Immunoglobulin
• Heavy chain
• Multiple myeloma
• Light chain amyloidosis