Fig. 1

The basic model components and possible paths to channel activation. Ca²⁺ is released from the nuclear envelope (NE) store and the effect of pumps is modelled as a uniform uptake into the NE. Channels are shown in green and pores in dark blue. In our model, CICR activation can fail for several reasons such as a low diffusion coefficient or large inter-channel distances. If the nucleosol has channels that are too far apart, Ca²⁺ cannot spread far and activate directly another channel (pink path). The red curve illustrates an alternative path to activation that exploits the more favourable cytosolic propagation conditions, with closer cytosolic channels