I detected 2 different immunoglobulin light chains by MALDI TOF MS/MS..their amino acids sequence were different, but both match to immunoglobulin light chain when searching through database.
Is it possible to see the nucleotide sequence difference through PCR amplification of the gene at genomic DNA level? I was told that it would be the same as gene rearrangement occurs in matured B cells which leads to that different in amino acids sequence, any comments?
Depending upon the species you are working with--there may be up to 4 different light chain isotypes, all of which are based upon the sequence of the constant region. Yes, you can classify IgH and IgL isotypes using PCR based cloning and sequencing reactions. The constant regions are just that--constant--they do not change. Variable regions can change through a process known as somatic hypermutation (SMH)--this is antigen driven event.
Indeed you can have a lot of different sequences for a light chain (as well as for a heavy chain): apart from the isotypes which stem from differences in the constant region (they can be either kappa or lambda) you can have many differences due to the rearrangement of several exons from which each B lymphocyte to be can chose from to form a definitive exon for the so call variable region. Appart from the exon each B lymphocyte chooses, there are differences depending on how they paste the chosen eons together (by adding nucleotides to the region in between) and finally when they find the antigen they recognize the further undergo mutations in the variable exon in the process called somatic hypermutation than ends up with an improved affinity for the antigen. Thus you can have many different sequences for a light chain.
I don't think the question was simply about VJC RAG mediated rearrangments and P/N additions etc but more about the actual isotypes. If you are talking about the variable region--then yes, you can have a lot (100s-10,000s etc of unique VJ recom events) but if its about the constant region, then no-aside from allelic variants. And not all species are limited to just kappa and lambda.
- Badges
- Science topic
- Similar topics
- Biological Science
- Immunology