Immunoglobulins- Explained

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Immunoglobulins- Explained

  1. 1. Immunoglobulins
  2. 2. Structure of Immunoglobulin molecule Variable Region (VL & VH) Disulphide Bonds Light chain(kappa and lambda) Heavy Chain Hinge
  3. 3. Structure of Immunoglobulin molecule • Fab – Ag binding – Specificity determined by VH and VL – Block the active sites of toxins or pathogen-associated molecules. Papain • Fc – Effector functions – Trafficking of antigens into the antigen processing pathways. – Complement Binding – Binding to the cells like mast cells, granulocytes, macrophages
  4. 4. In an immunoglobulin molecule, what is the structural basis for the infinite diversity needed to match the antigenic universe?
  5. 5. Variable Region of Fab Segment COMPLEMENTARITY DETERMINING REGIONS (CDR) – These are hypervariable regions that have antigen contact points. FRAMEWORK REGION
  6. 6. Hypervariable CDRs are located on loops at the end. (Yellow Color)
  7. 7. Hypervariable loops and framework: Summary •The framework supports the hypervariable loops. •The sequences of the hypervariable loops are highly variable amongst antibodies of different specificities. •The variable sequences of the hypervariable loops is also influenced by the shape, hydrophobicity and charge at the tip of the antibody. •Variable amino acid sequence in the hypervariable loops accounts for the diversity of antigens that can be recognised by a repertoire of antibodies.
  8. 8. Isotypes, Allotypes, and Idiotypes of Immunoglobulins 1. ISOTYPES All the heavy chain constant region structures which give rise to classes and subclasses are expressed together in the serum of a normal subject are called Isotypic variants. (IgG, IgA, IgM, etc) Each of those is called Isotype. 2. ALLOTYPES Inherited small, functionally insignificant, structural differences, especially in the constant portion of the antibody cause by the difference of amino acid sequence. The variations in heavy chain genes are called Allotypes. 3. IDIOTYPE The variations of amino acid sequences within the variable domains on light and heavy chains are called Idiotypes.
  9. 9. …to make things easy! Isotype: Present in ALL members of the same species (ALL humans); ie., same for all humans. Allotype: Present in members of the same family, same ethnic group, etc. Used for paternity testing. Idiotype: Different for each and every individual.
  10. 10. Thank you very much!

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