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Mechanistic Bases for Privileged Capture and Unidirectional Targeting of Tail-Anchored Proteins by the Get3 ATPase


Chio, Un Seng (2019) Mechanistic Bases for Privileged Capture and Unidirectional Targeting of Tail-Anchored Proteins by the Get3 ATPase. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/S1CD-5Z42.


C-terminal tail-anchored membrane proteins (TAs) are targeted post-translationally to the endoplasmic reticulum (ER) in eukaryotic cells mainly through the Guided entry of tail-anchored protein (GET) pathway. Here we use biochemical and biophysical approaches to shed further mechanistic insight into how the central chaperone, the Get3 ATPase, is able to capture TA substrates in a privileged manner and provide unidirectional targeting to the ER.

Specifically, we first show in Chapter 2 that Get3 dynamically samples open and closed conformations as a "protean clamp". Binding of TA substrates induces Get3 to sample more open conformations that causes Get3 to dissociate from the cytosolic regulatory Get4/5 complex, hydrolyze ATP, and become primed to interact with the Get1/2 membrane receptors. Therefore, a TA substrate acts as the switch for unidirectional targeting, transitioning Get3 from a "TA-loading mode" to a "membrane targeting mode". Next, in Chapter 3, we show that a small, conserved alpha-helical lid motif, known as α8, lining the substrate binding groove is necessary for Get3 to efficiently capture TA substrates in a privileged manner over competing off-pathway chaperones.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Protein targeting, chaperones, tail-anchored proteins, membrane proteins, ATPases, single-molecule spectroscopy, protein dynamics
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Shan, Shu-ou
Thesis Committee:
  • Clemons, William M. (chair)
  • Hoelz, Andre
  • Dougherty, Dennis A.
  • Shan, Shu-ou
Defense Date:11 December 2018
Non-Caltech Author Email:unsengc (AT)
Funding AgencyGrant Number
Gordon and Betty Moore FoundationGBMF2939
Record Number:CaltechTHESIS:01112019-160835213
Persistent URL:
Related URLs:
URLURL TypeDescription article; certain sections were adapted for Ch 1. adapted for Ch 2. adapted for Ch 3.
Chio, Un Seng0000-0002-5295-2690
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11340
Deposited By: Un Seng Chio
Deposited On:31 Jan 2019 23:58
Last Modified:04 Oct 2019 00:24

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