Antibody-1 - Antibodies 1. So, what is an antibody and how...

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Antibodies 1. So, what is an antibody and how are they made? A. Antibodies proteins that are composed of two (identical) proteins called heavy chains and two (identical) proteins called light chains that are covalently bonded to form an antibody monomer. (Fig. 16.5) 1) Fab= antigen binding fragment made from heavy and light chain variable regions. The arms of the Y make up the Fab regions 2) Fc constant region-made only from heavy chain. The stem of the Y makes up the Fc region. B. Once fully activated by an effector Th2 cell, the B cell will switch to a different isotype of antibody which is most effective for this specific pathogen. 1) There are 3 possible changes: from μ-- γ, ε, α . These cassettes are responsible for making a different class of antibody (Fig. 16.22) a. IgD is never secreted and is only found as a BCR on naïve B cells. b. IgM is made until the DNA is arranged to make a proper heavy chain. 2) When a B cell switches constant regions, the genetic cassettes used to create the variable region of both the heavy and light chains will remain the same. The constant region is the one that changes and the variable region stays the same – opposite of what you would think C. Since a single B cell can make only one specific antibody, it also uses this antibody as its BCR. The only difference between the BCR and the antibody a B cell secretes is a membrane spanning domain that allows the antibody to be inserted into the cell’s plasma membrane (Fig. 16.13) 1) When a B cell switches Fc regions, the BCR on the clonal offspring will be the same as the antibody it secretes (secretes IgG, has IgG as its receptor). As the IgM or IgD starts
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This note was uploaded on 03/28/2010 for the course MCRO 251 taught by Professor Lorrainecramer during the Fall '09 term at UNC.

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Antibody-1 - Antibodies 1. So, what is an antibody and how...

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