Fish Immunology (1+1)

Unit 2 - Evolution of immune system

2.2. The invasion of recombination-activating gene transposon (RAG transposon)
The gene encoding an immunoglobulin superfamily (IgSF) exon was invaded by the recombination-activating gene transposon (RAG transposon) and invasion of this transposon helped in triggering B cell receptor and T cell receptor based immunity. RAG genes are present in all gnathostomes but not in jawless fish, and this suggest the reason for the absence of B cell receptor and T cell receptor in jawless fishes. RAG transposon activity is the major incident in the evolution of adaptive immunity, because the jawed vertebrates have an advance mechanisms and molecules that are involved in adaptive immunity when compared with jawless fish.