| Title: | BiP acts as a molecular ratchet during posttranslational transport of prepro-alpha factor across the ER membrane |
| Author(s): | Matlack KE; Misselwitz B; Plath K; Rapoport TA; |
| Address: | "Howard Hughes Medical Institute, Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115-6091, USA" |
| DOI: | 10.1016/s0092-8674(00)80767-9 |
| ISSN/ISBN: | 0092-8674 (Print) 0092-8674 (Linking) |
| Abstract: | "We have addressed the mechanism by which proteins are posttranslationally transported across the membrane of the yeast endoplasmic reticulum (ER). We demonstrate that BiP (Kar2p), a member of the Hsp70 family resident in the ER lumen, acts as a molecular ratchet during translocation of the secretory protein prepro-alpha factor through the channel formed by the Sec complex. Multiple BiP molecules associate with each translocation substrate following interaction with the J domain of the Sec63p component of the Sec complex. Bound BiP minimizes passive backward movements of the substrate through the channel, and BiP's subsequent dissociation results in a free polypeptide in the ER lumen. Antibodies against the substrate can replace BiP, indicating that a Brownian ratchet is sufficient to achieve translocation" |
| Keywords: | "Amino Acid Sequence Cloning, Molecular Endoplasmic Reticulum/*metabolism Escherichia coli Fungal Proteins/chemistry/*metabolism HSP70 Heat-Shock Proteins/chemistry/*metabolism Intracellular Membranes/metabolism Kinetics Mating Factor Molecular Sequence Da;" |
| Notes: | "MedlineMatlack, K E Misselwitz, B Plath, K Rapoport, T A eng GM54238/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 1999/06/15 Cell. 1999 May 28; 97(5):553-64. doi: 10.1016/s0092-8674(00)80767-9" |
