Antibody Structure And Function PDF

STRUCTURE AND FUNCTION OF DIFFERENT TYPES OF ANTIBODY DEPARTMENT OF MICROBIOLOGY DR. SHAKUNTALA MISRA NATIONAL Rehabilitation UNIVERSITY SUBMITTED TO SUBMITTED BY  WHAT IS ANTIBODY  An antibody, also known as an immunoglobulin, is a Y-shaped prote...

STRUCTURE AND FUNCTION OF DIFFERENT TYPES OF ANTIBODY DEPARTMENT OF MICROBIOLOGY DR. SHAKUNTALA MISRA NATIONAL Rehabilitation UNIVERSITY SUBMITTED TO SUBMITTED BY  WHAT IS ANTIBODY  An antibody, also known as an immunoglobulin, is a Y-shaped protein produced mainly by plasma cells that is used by the immune system to identify and neutralize pathogens such as bacteria and viruses.  The first use the term “antibody” occurred in a text by Paul Ehrlich.  Antibody are secreted by B cells of the adaptive immune system, mostly by differentiated B cells called plasma cells.  STRUCTURE OF ANTIBODY The antibody is a ‘Y’ shaped molecule. Each immunoglobin molecule is made up of four polypeptide chains. There are two heavy or H-chains and two light or L-chains. The four polypeptide chains are held together by disulfide bonds (-s s-)to form a Y shaped structure.  The region holding the arms and stem of the antibody is termed the hinge. Fab fragment is a region on an antibody that binds to antigens. It Is composed of one constant and one variable domain of each of the heavy and the light chain. Variable region constitute the antigen binding site (paratope). Fc region is the tail region of an antibody that interacts with cell surface receptors called Fc receptors and some proteins of the complement system. This property allows antibodies to activate the immune system. This part of the antibody recognizes and binds to the specific antigen to form an antigen antibody complex. Since most antibody carry two antigen binding sites ,they are said to be bivalent.  TYPES OF ANTIBODY IgG IgM IgA IgE IgD IgG STRUCTURE Immunoglobulin G (IgG) antibodies are large globular proteins with a molecular weight of about 150 kDa made of four peptide chains. It contains two identical γ (gamma) heavy chains of about 50 kDa and two identical light chains of about 25 kDa, thus a tetrameric quaternary structure. FUNCTION IgG provides long term protection.  IgG protects against bacteria, viruses, neutralizes bacterial toxins, triggers complement protein systems and binds antigens to enhance the effectiveness of phagocytosis.  IgM STRUCTURE Immunoglobulin M (IgM) antibodies are constructed of five units (i.e. mostly as pentamers) which are each comprised of two heavy-chains (μ-chains) and two light chains, bound together by disulfide bonds and a so-called J-chain. FUNCTION IgM populations rise very quickly when the body is first confronted with an infectious organism. It binds to antigen and activate the complement system ,which helps to destroy pathogens and prevent their invasion of blood.  IgA Structure Immunoglobulin A (IgA) antibodies consist of heavy (H) and light (L) chains. Each H chain is comprised of the constant region , hinge region and the Variable (V) region. Light chains consist of the CL and Vκ or Vλ elements. FUNCTION Immunoglobulin A (IgA) is primarily found in mucosal tissues, such as those in the mouth, vagina, and intestines, as well as in saliva, tears, and breast milk.  IgE STRUCTURE Immunoglobulin E (IgE) antibodies have only been found in mammals. IgE is synthesized by plasma cells. Monomers of IgE consist of two heavy chains (ε chain) and two light chains, with the ε chain. FUNCTION Immunoglobulin E (IgE) is the antibody responsible for the allergic response. IgE bind to mast cells and basophils which participate in the immune response.  IgD STRUCTURE Immunoglobulin D (IgD) antibodies are expressed in the plasma membranes of immature B-lymphocytes. IgD is also produced in a secreted form that is found in small amounts in blood serum. FUNCTION Function of IgD is to signal the B cells to be activated.IgD plays a role in the induction of antibody production. DIFFERENT TYPES OF ANTIBODIES :- References https://www.sinobiological.com/resource/antibody-technical/antibody-structure-function. figure from Shaalaa.com Slideshare.com kuby book THANKYOU