immunoglobuliinimolekyylin

Immunoglobuliinimolekyyli, commonly known as an antibody, is a Y-shaped protein produced by plasma cells, a type of white blood cell. Its primary function is to identify and neutralize foreign objects such as bacteria, viruses, and other pathogens. Each antibody is highly specific, meaning it can bind to a particular antigen, a unique molecular structure found on the surface of these foreign invaders.

The structure of an immunoglobuliinimolekyyli consists of four polypeptide chains: two identical heavy chains and two identical light chains. These chains are held together by disulfide bonds. The "Y" shape arises from the arrangement of these chains, with the tips of the "Y" arms forming the antigen-binding sites. The base of the "Y" is the constant region, which interacts with other components of the immune system.

There are five main classes of immunoglobulins in humans: IgG, IgM, IgA, IgD, and IgE. Each class has a distinct structure and function. IgG is the most abundant in serum and plays a crucial role in neutralizing toxins and protecting against infections. IgM is the first antibody produced during an immune response and is effective at agglutinating (clumping) pathogens. IgA is found in secretions like tears, saliva, and breast milk, providing mucosal immunity. IgD is primarily found on the surface of B cells and is involved in B cell activation. IgE is associated with allergic reactions and defense against parasitic infections.