FIGURE 2.

Model of the human T cell receptor. Each T lymphocyte displays two recognition units on its surface: the Ti-T3 complex and the associative recognition structure, T8 or T4. The T8 and T4 glycoproteins bind to non-polymorphic regions of class I and class II MHC gene products respectively. Note that the precise domains of class I and class II that the T cells recognize are unknown and assigned in the figure only for purposes of illustration. The Ti molecules, unique to each T cell recognize specific antigen in the context of a polymorphic MHC gene product, while the T3 molecules, common to all mature T cells, are involved in signaling the cell interior. Redrawn from Reinherz et al. (1983b).