Fig. 8

Model of proteasome dynamics under oxidative and salt stresses. Cellular 26S proteasome is dynamically assembled and disassembled from 19S RP and 20S CP, and associates with chaperones such as HSP70, as well as alternate caps, including PA200. Oxidative and salt stresses both diminish the association between the 19S RP and the 20S CP, and oxidative stress may trigger 26S proteasome dissociation indirectly through a reduction in cellular ATP content. Activity of the dissociated or free 20S proteasome is increased under oxidative stress, possibly due to its greater propensity for the open state or higher affinity to oxidized and misfolded proteins. While the 20S proteasome also exhibits reduced association with HSP70s under oxidative stress, salt stress causes decreased interaction with proteasome associated proteins, such as PA200. Note that the proteasome particles and associated proteins are not drawn in scale