Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published October 10, 2017 | Published + Supplemental Material
Journal Article Open

A protean clamp guides membrane targeting of tail-anchored proteins


Proper localization of proteins to target membranes is a fundamental cellular process. How the nature and dynamics of the targeting complex help guide substrate proteins to the target membrane is not understood for most pathways. Here, we address this question for the conserved ATPase guided entry of tail-anchored protein 3 (Get3), which targets the essential class of tail-anchored proteins (TAs) to the endoplasmic reticulum (ER). Single-molecule fluorescence spectroscopy showed that, contrary to previous models of a static closed Get3•TA complex, Get3 samples open conformations on the submillisecond timescale upon TA binding, generating a fluctuating "protean clamp" that stably traps the substrate. Point mutations at the ATPase site bias Get3 toward closed conformations, uncouple TA binding from induced Get3•Get4/5 disassembly, and inhibit the ER targeting of the Get3•TA complex. These results demonstrate an essential role of substrate-induced Get3 dynamics in driving TA targeting to the membrane, and reveal a tightly coupled channel of communication between the TA-binding site, ATPase site, and effector interaction surfaces of Get3. Our results provide a precedent for large-scale dynamics in a substrate-bound chaperone, which provides an effective mechanism to retain substrate proteins with high affinity while also generating functional switches to drive vectorial cellular processes.

Additional Information

© 2017 National Academy of Sciences. Edited by Taekjip Ha, Johns Hopkins University, Baltimore, MD, and approved September 5, 2017 (received for review May 25, 2017). Published online before print September 26, 2017. We thank Xavier Michalet and Antonino Ingargiola for help with analysis of μs-ALEX data; H. Cho, M. Rao, and S. Wang for reagents; the D. A. Dougherty laboratory for use of HPLC; and W. M. Clemons, A. Hoelz, R. Deshaies, M. Zimmer, T. F. Miller, M. Rome, and members of the S.-o.S. and S.W. laboratories for critical discussions and comments on the manuscript. This work was supported by NIH Grant GM107368, Gordon and Betty Moore Foundation Grant GBMF2939, and a fellowship from the Weston Havens Foundation (to S.-o.S.). Author contributions: U.S.C. and S.-o.S. designed research; U.S.C. and S.C. performed research; S.W. contributed new reagents/analytic tools; U.S.C. and S.C. analyzed data; and U.S.C. and S.-o.S. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1708731114/-/DCSupplemental.

Attached Files

Published - PNAS-2017-Chio-E8585-94.pdf

Supplemental Material - pnas.201708731SI.pdf


Files (5.3 MB)
Name Size Download all
2.8 MB Preview Download
2.6 MB Preview Download

Additional details

August 21, 2023
October 17, 2023