Summary
V(D)J recombination and somatic hypermutation generate billions of distinct receptors and antibodies.
In depth
Gene segments V, D and J are randomly joined by RAG enzymes, with junctional diversity from added nucleotides, generating over 10^11 possible antibodies from few genes. Somatic hypermutation and selection refine affinity. Susumu Tonegawa won the 1987 Nobel Prize.
RAG1/2 cut at recombination signal sequences. Light chains rearrange V and J only. Allelic exclusion ensures one specificity per B cell.
Remember: this somatic recombination happens in the immune cells only, not in the germline.
The heavy chain has about 40 V, 25 D and 6 J segments, and light chains add more; combinations alone give around 10 to the 6 different antibodies, then junctional diversity (addition of N and P nucleotides, trimming), pairing of heavy and light chains and somatic hypermutation raise the repertoire to more than 10 to the 11. RAG1 and RAG2 recombinases cut at recombination signal sequences, and defects cause SCID.
Susumu Tonegawa won the 1987 Nobel Prize for showing that antibody genes rearrange in B cells. Allelic exclusion ensures each B cell expresses only one heavy and one light chain. T cell receptors use similar mechanisms but do not hypermutate.
Key idea: the immune system generates diversity by cutting and pasting DNA in somatic cells, an exception to the idea that all cells have identical genomes.
Frequently asked questions
What is Antibody Diversity?
V(D)J recombination and somatic hypermutation generate billions of distinct receptors and antibodies.
Which area of biology covers Antibody Diversity, and how advanced is it?
Antibody Diversity is one of the 52 topics in Immunology & Disease. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Antibodies, B Lymphocytes, Clonal Selection.
Can you give an example of Antibody Diversity?
AID enzyme deaminates cytosine in germinal centre B cells.
What should I learn before Antibody Diversity?
Work through the Beginner topics in Immunology & Disease first, such as Immune System, Viruses, Innate Immunity, then return to Antibody Diversity. Advanced topics assume the Intermediate vocabulary.
What topics are related to Antibody Diversity?
The closest topics to Antibody Diversity are Antibodies, B Lymphocytes, Clonal Selection, Phagocytosis. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Antibody Diversity?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Antibody Diversity. To practise the whole of Immunology & Disease, use the Immunology & Disease quiz.
How is Antibody Diversity different from Antibodies?
Antibody Diversity: V(D)J recombination and somatic hypermutation generate billions of distinct receptors and antibodies. Antibodies: Y-shaped proteins made by B cells that bind specific antigens and mark them for destruction. Read both side by side and note what each one explains.
How should I study Antibody Diversity step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Antibodies and explain the difference aloud. Finally, take the Immunology & Disease quiz and come back to this page for any question you miss.