Figure 1.

V(D)J recombination at the tcrg (upper panel) and tcra/tcrd (lower panel) locus. Only the functional gene segments are shown. The TCR-γ chain is produced using only a single V-J recombination, with P/N additions occurring at the V-J junction. The TCR-δ chain is produced using V-D-J recombinations that can involve either 2 or 3 D segments, leading to the creation of up to 4 N diversity regions. For the clarity of the figure, only the gene segments that can be used in TCR-δ chain production are presented (lower panel). The organisation of loci tcrg and tcra/tcrd was adapted from IMGT database.³