Figure 3.

PKCθ is functionally coupled to CD28 costimulation. (a) Jurkat T cells were transfected with an empty vector (−) or wild-type PKCθ (+) together with CD28RE/AP-1-Luc. After 20 h, cells were stimulated for an additional 6 h with CD3- and/or CD28-specific antibodies. Normalized luciferase activity in cell lysates was quantified as in Fig. 2. (b) CD28RE/AP-1-Luc activity in Jurkat T cells cotransfected with an empty vector (−) or with a c-Myc-tagged Tat plasmid together with constitutively active PKC-θ, -α, -ζ, or -ɛ mutants. The expression level of Tat or PKCθ was analyzed by Western blotting, and equal protein loading was confirmed by anti-actin immunoblotting (Lower).