Science Focus
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Our adaptive immune system, the one that responds to specific pathogens, relies on T cells and B cells. These cells make proteins that have a key job: distinguish between the harmless proteins in all of our cells and foreign proteins that may be harmful. In T cells, these molecules are creatively called T cell receptors (TCRs), and in B cells they are antibodies.
Each individual has a unique set of TCRs and antibodies—their immunorepertoire—selected by the interplay between her genetic makeup and the proteins to which she's been exposed. But which of these two factors dominate?
The region of the genome that encodes these molecules is super complex. It consists of genetic cassettes that are linked in different combinations to generate diverse receptors that can recognize many potential invaders. First there are about 50 segments of DNA called V, for variable; next come a bunch of D segments, for diversity; then J for joining; and lastly C for the constant region at the base of these receptors. In a process called V(D)J recombination, each T cell and B cell picks one V segment, one D segment, and one J segment, then links them up to make a complete gene that includes a unique protein binding site.
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original post: http://feeds.arstechnica.com/~r/arstechnica/science/~3/wVtdQWljwRg/
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