Figure 4.

PI3K-C2β is required for maximal Ca²⁺ flux in Jurkat-KCa3.1 cells. (i and ii) A representative trace of 340/380 fura-2 fluorescence ratio from Jurkat T-cells or Jurkat-KCa3.1 T-cells transfected with GFP, GFP-PI3K-C2β, or a siRNA to PI3K-C2β. Cells were loaded with Fura-2 AM (5 μM) for 30 min, and the fluorescence measurements were made at RT. Fura-2 fluorescence was recorded (Delta Ram; PTI) at excitation wavelengths of 340 and 380 nm after cross-linking with anti-CD3 antibodies as indicated. (iii) Bar graph summary of peak 340/380 fluorescence after perfusing the cells with 2 mM Ca²⁺. Average values from 50–70 cells are shown for each condition. *p < 0.05 compared with fluorescence values of Jurkat-KCa3.1 alone and as indicated.