The door to the ER is closed by BiP-ADP and opened with BiP-ATP.

Agate that guards the translocon is opened and closed by ATP cycles that also give the same protein chaperone activity, as shown on page 389 by Alder et al.

The translocon is an aqueous pore in the ER membrane through which secreted proteins pass during translation. To prevent the unwanted passage of ions, unused pores are plugged on the lumen side by the action of BiP. Within the ER, BiP is also an Hsp70-like chaperone. Alder et al. now find that the ATP-dependent changes in substrate affinity that make BiP an efficient chaperone also give it its translocon gating ability.

ADP-bound Hsp70 chaperones bind tightly to their substrates, whereas ATP induces a conformational change that opens the substrate-binding pocket. Cycles of binding and release allow BiP to help its substrates fold properly....

The Rockefeller University Press
2005
The Rockefeller University Press
2005
You do not currently have access to this content.