Skip to main content
. 2011 Sep 13;9(9):e1001149. doi: 10.1371/journal.pbio.1001149

Figure 7. Model for superantigen action through binding to CD28.

Figure 7

Structural model for Th1 cell activation by superantigens through simultaneous binding to CD28, MHC-II, and TCR. SEC3 (cyan), a close relative of SEB, in complex with TCR Vβ (green) and MHC-II (red) extracellular domains (1jck.pdb; [38]). The SEC3 β-strand/hinge/α-helix domain in magenta is freely accessible to the N-terminal 118-residue portion of the CD28 extracellular domain (1yjd.pdb; [21]). CD28 homodimer interface peptides (Figure 4A) are shown: p1TA (HVK resolved in 1yjd.pdb is red), p2TA (green), p3TA (pink), p4TA (grey), and p5TA (SNGTII is blue); MYPPPY is yellow. CD28 and TCR are oriented such that their trans-membrane domains (not shown) can enter the T cell at top; the MHC-II is oriented towards the antigen-presenting cell at bottom; for simplicity, cell surfaces are not shown.