Fig. 2. TCR complex interaction with peptide-MHC complex (pMHC).

A) TCR components (ectodomains, stalk connecting peptides [CP; depicted as red, blue, chartreuse, and turquoise lines], transmembrane [TM] segments and cytoplasmic tails) are labeled and shown in distinct colors. An enlarged view is shown in the box. Note that the single acid residue in each CD3 subunit is omitted here for clarity. The pMHC on the APC and the interacting CD8αβ co-receptor are not colored. In each panel, the Cβ FG loop is depicted by an asterisk (*). B) Lateral view of TCR receptor components in ribbon form (PDB:IFND, 1XM and 1JBJ) oriented above the T-cell membrane (grey). Adducted sugars are depicted in beige in space-filling (CPK) representation. CD3ζζ is absent since it lacks ecotodomains. C) Force on TCR-pMHC interaction initiates signaling (pMHC, orange; Cβ FG loop, magenta; and TCR complex, other colors). This figure was rendered by Steve Moskowitz of Advanced Medical Graphics, Boston, MA. See accompanying supplemental movies 1 and 2.