Antibody Heavy and light chains - YouTube
23/07/2014 · Antibody Heavy and light chains ..
What “flips” the switch? Notice in and that the constant-region gene segments defining different antibody heavy-chain classes are arranged in tandem a VDJ region. The mechanism by which a B cell switches to make IgG (C regions gamma 1–4), IgE (C-epsilon), or IgA (C-alpha 1 and 2) is very similar to VDJ formation. Each constant segment, except delta, contains a repeating DNA base sequence called a . Recombination between these switch regions will delete the intervening DNA between the VDJ region and one of the constant regions. The primary RNA transcript produced after this recombination event has all of its introns spliced out before translation. Because the VDJ region is the same regardless of which CH gene is selected, the antibody produced will have the same antigenic specificity as the original IgM. However, the heavy-chain switch selection process is random. The type of cytokine present at the time of the switch will influence which CH gene is selected.
Lambda Light Chain Antibody - Thermo Fisher Scientific
Where does the rest of antigen-binding-site diversity arise? After recombination, the V regions of the germ lines are susceptible to high levels of somatic mutation (called hypermutation), resulting in the hypervariable regions. Hypermutation happens every time a memory B cell is exposed to the antigen; the memory B cells divide and the hypervariable regions mutate. Additional diversity comes from the junctions of VJ and VDJ, where recombinational joining can occur between different nucleotides. Each gene recombination event can generate additional codons, so the resulting peptides will differ by one or more amino acids. The interactions between the light- and heavy-chain hypervariable regions in an antibody form the antigen-binding sites.