FIG. 3.

SUMOylation impairs Ca²⁺-dependent exocytosis. A: Exocytotic capacitance responses to depolarizations of increasing duration (10, 320, and 2560 ms shown) of INS-1 832/13 cells expressing GFP, SUMO1-YFP, or SUMO1-YFP + SENP1. B: Average capacitance responses from A plotted vs. depolarization duration. C: The whole-cell capacitance response of INS-1 832/13 cells measured during direct application of 200 nmol/L free Ca²⁺ via the patch pipette. D: The average capacitance response of cells expressing GFP, SUMO1-YFP, or SUMO1-YFP + SENP1 at 200 s following initiation of Ca²⁺ infusion and normalized to initial cell size. E: Endogenous and overexpressed Ubc9 in INS-1 832/13 cells (left). Exocytotic capacitance responses (right) in INS-1 832/13 cells expressing GFP or Ubc9 and dialyzed with either GST or SENP1. F: Average cumulative capacitance responses over the series of 10 depolarizations. **P < 0.01; ***P < 0.001 vs. GFP.