A new T Cell Receptor in Squamata Reptiles

Squamata exhibit a loss of genes for the gamma/delta T-lymphocyte receptor chains and a significant decrease in the number of V genes at the TRBV locus. Through genome analysis, I have discovered a new locus that contains V, J, C, and TM genes that have a similar structure to the classical TCR chains. This gene is viable, as demonstrated by the presence of messenger RNAs in the transcriptomes. Analyses using the AlphaFold2 program indicate that the deduced protein chain is associated with the alpha chain of the TCR. I have named this new chain “epsilon,” and it forms a new TCR alpha/epsilon. Evolutionarily, the epsilon chain arose from a duplication of the beta chain gene at the time of the divergence of amphibians and reptiles and has since been specifically maintained in Squamata.