Figure 1.

Ca²⁺ circuits are created with different membrane systems by the coordinated regulation of influx and efflux pathways (top). Evidence indicates that a loss of specific endomembrane efflux pathways can result in a greater magnitude and prolonged duration of a Ca²⁺ signature that correlates with triggering cell death (bottom). Not indicated in the figure is the role of Ca²⁺ buffering, which can affect flux rates and magnitudes [57].