- Are glycoprotein belonging to Immunoglobulin superfamily.
- Large 'Y' shaped protein produced by B- Lymphocyte. It neutralize foreing object such as bacteria, virus,Fungus etc.
- Has Antigen binding site.
- Contain two heavy(H) chain and two light (L) chain. Each heavy chain consists of about 450 amino acids and each light chain consists of about 220 amino acids.
- Disulfide bond hold each light chain to heavy chain. This part of Antibodies is more flexible so it is called Hinge Region.Beyond the hinge region, part of the two heavy chain form stem region.
- Most Antibodies have two antigen binding site, thay are said to be bivalent.
- Each antibody has a variable region at the top of the arms
Types of Immunoglobulin are:
IgG
1. Found in all fluid, smallest but most common Antibodies (70 - 80%).
2. Monomer structure
3. Very important for fight againest the bacteria and virus.
4. Can cross the placenta.
IgM
1. Largest antibody.
2. Found in the blood and lymph fluid, are the first type of antibody made in response to infection.
3. About 5 - 10 % of all the antibodies in in body.
4. pentamer monomer structure.
IgA
1. Found in nose, GI tract, respiratory tract, ears, eyes and vagina.
2. Also found in saliva, tear, blood.
3. About 10 - 15 % of all the antibodies in in body.
4. Small number of people do not make IgA antibodies.
5. Found in breast milk.
6. Monomer, Dimer, Trimer structure.
IgD
1. About 0.2 % of all the antibodies in in body.
2. Found in small amount in tissue they lines the belly and ches.
3. Monomer structure.
IgE
1. Less than 0.1 % of all the antibodies in in body.
2. Found in Lungs, Skin, Mucous membrane.
3. Monomer structure.
4. Involve in allergic reaction.
