FIGURE 2.

Functional activity of mutants transiently transfected into IP₃R null DT40 cells. DT40 TKO cells were transiently transfected with the indicated IP₃R constructs by electroporation. Cotransfection with dsRed was used to identify transfected cells. After 48 h the cells were used for Ca²⁺ imaging experiments as described under “Experimental Procedures.” The cells were stimulated with anti-IgM (1 μg/ml added at arrows). Representative traces from three cells are shown or each mutant (panels a–n), and the total number of responding cells in a minimum of two coverslips from separate transfections is indicated in each panel.