Fig. 6: Model of the conformational plasticity of the BiP–GRP94 complex along the GRP94 chaperone cycle.
From: Conformational plasticity of a BiP–GRP94 chaperone complex
In the preloading complex, one BiP molecule is bound to an open GRP94 dimer, which is in the apo or ADP-bound state. The binding of a second BiP molecule supports transitioning into the loading complex, where GRP94 is in a semiclosed conformation. ATP binding to GRP94 may support the partial closure of the ATP lid and GRP94NTD dimerization under physiological conditions. A similar effect may be produced by PU-WS13. Both BiP molecules bound to GRP94 reside in the ADP-bound, domain-undocked conformation. Finally, the GRP94 dimer transitions into the fully closed state and BiP concurrently dissociates. We presume that ATP binding to BiP drives this process. The relative position of the GRP94NTD semiclosed dimer interface is indicated in purple.
