Figure 1.

ER stress-sensing model schematic. In the lumen of the ER, unfolded proteins are bound by the chaperone BiP, which aids folding. Eventually, the stable folded proteins are released from the folding complex, and exported from the ER. The folding process is monitored by the transmembrane stress-sensing proteins Ire1 and Perk. In our model, ER stress is measured through one of the three mechanisms depicted in the bottom panel, and transmitted as stochastic time series of the transmembrane sensor activation. (Online version in colour.)