Cell & Developmental Biology
Open Access

Structural Regions of an Antibody and Functional Characteristics of B and T Cells

Abdel Khader^{* *}Correspondence: Abdel Khader, Department of Cell Science Research, University of Al-Salam, Al-Salam, Iraq, Email:

Author info »

Description

A Y-shaped protein called an immunoglobulin (Ig), also called an Antibody (Ab), is used by the immune system to recognize and eliminate foreign invaders like dangerous bacteria and viruses. The antibody recognizes the antigen, or distinguishing infection molecule. Each "Y" tip of an antibody possesses a paratrooper (like to a lock) that is specific for one specific epitope (similar to a key) on an antigen, making it feasible for these two structures to bind together exactly. A pathogen or an infected cell can either be quickly neutralized or designated by an antibody for attack by other immune system components via this binding mechanism (for example, by blocking a part of a virus that is essential for its invasion). The immune system can recognize millions of different antigens to the equally diversified antigen-binding sites at both tips of the antibody. Nonetheless, the leftover antibody is frequently stable. The only types that specify the antibody's class or isotype are IgA, IgD, IgE, IgG, and IgM. The constant region at the antibody's trunk contains sites that are involved in interactions with several immune system components. So, the class influences the function that an antibody starts after adhering to an antigen in addition to some structural traits. Different antibodies have different locations in the body where they are released as well as different times throughout an immune response. Together with B and T cells, antibodies are the most important element of the adaptive immune system. There are two different kinds of them: One that is associated to a B cell and the other, a soluble variety, which is not attached and is present in extracellular fluids like blood plasma. All antibodies start out in their initial state attached to a B cell's surface. They're referred to as B-Cell Receptors (BCR). The B cell is activated, multiplies, and develops into memory B cells or plasma cells when an antigen binds to a BCR. These cells stay in the body and produce soluble antibodies that have the same paratope to offer long-lasting protection to the antigen. There are many secretions produced, including soluble antibodies and fluids from the blood and tissues. Because these chemicals were traditionally known as humours, antibodymediated immunity may also be referred to as humeral immunity. The soluble Y-shaped units can exist as monomers or as a component of complexes with two to five units. Antibodies are made of immunoglobulin superfamily glycoproteins. Notwithstanding the widespread confusion between the terms "antibody" and "immunoglobulin," "antibody" can also refer to the secreted, soluble form of an antibody that does not contain B-cell receptors.

Structure

The three globular regions of an antibody, which approximately resemble a Y shape, are made of large (150 kDa) proteins that are 10 nm in size. Four polypeptide chains make up an antibody unit in humans and the majority of other mammals: Two identical heavy chains, two identical light chains, and two identical light chains connected by disulphide bonds. Each chain is composed of a number of domains, each of which is about 110 amino acids long and has a recognizable structure. Typically, these domains are represented by rectangles in simplified diagrams. Light chains only have one Variable Domain (VL) and One Constant Domain (OCL), but heavy chains have one variable domain (VH) and three to four Constant Domains (CH1, CH2, etc). The Fc, which forms the Y-shaped trunk of an antibody, and two Antigen- Binding Fragments (Fab), each of which contains a VL, VH, CL, and CH1 domains, are responsible for its structural division.

CONCLUSION

There is a flexible region of the heavy chains called the hinge that allows antibodies to attach to pairs of epitopes at various distances, form complexes (such dimers or trimmers), and bind effector molecules more quickly. Antibodies mainly migrate to the gamma globulin fraction in a blood protein electrophoresis test. On the other hand, the bulk of gamma-globulins are antibodies, which is why the terms Ig and were previously used synonymously. This alternate term was no longer in use due to incorrect correspondence and misunderstanding with (gamma) heavy chains, which identify the IgG class of antibodies.