Further characterization of T cell receptor chains of marsupials

cDNA clones encoding T cell receptor alpha (TCR alpha) and beta (TCR beta) from the South American opossum, Monodelphis domestica were isolated and ch aracterized. A single clone isolated encoding a TCR alpha chain was full le ngth, containing the complete V (variable). J (joining) and C (constant) re gions. Three partial cDNA clones were isolated for TCR beta which contained complete C sequences. Phylogenetic analysis of the TCR V alpha revealed th at the M. domestica sequence and a sequence from the Australian brushtail p ossum. Trichosurus vulpecula, belong to separate V alpha families and inter sperse 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 C alpha and C beta sequences from M. domestica T. vulpecula. and other ver tebrates revealed that the marsupial TCR C grouped together forming a siste r group to eutherian mammals. (C) 2001 Elsevier Science Ltd. All rights res erved.