Fig. 1.

Schematic representations of early thymocyte development and the pTα chains used in this study. (A) Schematic of αβ versus γδ T cell lineage fate during early thymocyte development. Cells that do not express TCR complexes are blocked at the β-selection checkpoint. Weak signaling from the preTCR or TCRγδ drives commitment to the αβ T cell lineage, whereas strong signaling from the TCRγδ drives the development of γδ cells. DN, CD4⁻CD8⁻ cells; DP, CD4⁺CD8⁺ cells. (B) Schematic showing the four exons of the gene that encodes pTα and the proteins that are generated from the two known alternative splice products: pTα^a and pTα^b. The amino acid residues Asp²² (D22), Arg²⁴ (R24), Arg¹⁰² (R102), and Arg¹¹⁷ (R117) have been implicated in preTCR oligomerization.