Variability of Antibodies

[Kam3725]

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In regards to antibodies, what accounts for the huge variability of antibody formation? (Why are there so many different combinations of possible antibodies produced even though the precursor cells have the same DNA?)

Is it due to alternative splicing of the mRNA transcripts or is it due to gene/DNA shuffling accounting for the production of different mRNA transcripts altogether...or am I totally off here? =\

Additionally, where are B cells with the same antibodies as the body suppressed and what is the underlying mechanism?

Thanks

 

[hvairline]

You are right alternative mRNA splicing does indeed play some role in the variability of the light and heavy chains present in antibodies and BCRs. The greatest variability, however, is produced through a process called gene recombination. Even though it is generally true that all cells in our body have the same DNA, lymphocytes(B and T cells) are a fascinating exception. During their maturation in the bone marrow and thymus genes that code for the variable regions of antibodies(heavy and light chains) get shuffled around.Specifically the genes for that code for the light chain have several variable segments, joining segments and one constant part(which constitutes the nonvariable segment of the light chain).During gene recombination enzymes catalyze the mixing of the Variable segments and the Joining segments which are then joined together in a unique way to produce a extremely diverse final DNA sequence which will code for the light chain of the antibody. The same is true for the production of the heavy chain(the heavy chain genes also contain an additional segment called Diversity segment). Now millions of different light chains can combine with millions of different heavy chains to produce a virtually limitless array of antibodies that can bind to virtually all antigens. Gene recombination produces this variability. Hope this answers your question!