cDNA clones encoding T cell receptor alpha (TCRα) and beta (TCRβ) from the South American opossum, Monodelphis domestica were isolated and characterized. A single clone isolated encoding a TCRα chain was full length, containing the complete V (variable), J (joining) and C (constant) regions. Three partial cDNA clones were isolated for TCRβ which contained complete C sequences. Phylogenetic analysis of the TCR Vα revealed that the M. domestica sequence and a sequence from the Australian brushtail possum, Trichosurus vulpecula, belong to separate Vα families and intersperse with sequences from eutherian mammals. Similar to results described for marsupial and eutherian light chains, diversity at the V region of the TCR is ancient and maintained. In contrast phylogenetic analysis of the TCR Cα and Cβ sequences from M. domestica, T. vulpecula, and other vertebrates revealed that the marsupial TCR C grouped together forming a sister group to eutherian mammals.
- T cell receptor