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Mechanistic Studies of Tail-Anchored Membrane Protein Targeting to the ER


Fry, Michelle Yen (2022) Mechanistic Studies of Tail-Anchored Membrane Protein Targeting to the ER. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/b3yj-c572.


The successful biogenesis – synthesis, delivery, and insertion into designated membranes – of membrane proteins is a crucial cellular process. One particular class of membrane proteins, tail-anchored (TA) proteins have a single transmembrane domain (TMD) that this located at their C-termini and are targeted to membranes post-translationally. Multiple pathways have been identified to target TA proteins to the ER membranes, but designated pathways for targeting TA proteins to the mitochondria remain elusive. The most well understood ER TA protein pathway is the Guided Entry of Tail-anchored proteins (GET) pathway, consisting of six (fungal) or seven (metazoans) proteins, SGTA, Get1-5, and Bag6 (metazoans only), has nearly been studied exclusively in Opisthokants (fungi and metazoans). Here we employed a combination of x-ray crystallography, cryo-electron microscopy, computational modeling, cellular biology, fluorescent imaging, and bioinformatics in order to understand the underlying factors that regulate the targeting of these TA proteins to their correct membranes. Our work reveals that ER-bound TA proteins tend to have a hydrophobic face whereas mitochondria-bound TA proteins contain a charge following their TMD. This finding corroborates our observation that the first component of the GET pathway to interact with TA proteins, SGTA, falls in a category of other hydrophobic segment binding domains, dubbed STI1-domains. Structures presented here demonstrate that the overall structure of Get3 is conserved in organisms as distant as Excavats and Opistokonts, and slight conformational changes in the ATPase allows the described chaperone cascade of the GET pathway to progress. Together these results refine the model for TA protein targeting to the ER membrane.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:GET pathway; Protein Targeting; Tail-anchored Proteins; co-chaperones; Get3; ATPase; SGTA; Giardia intestinalis
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Biochemistry and Molecular Biophysics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Clemons, William M.
Thesis Committee:
  • Shan, Shu-ou (chair)
  • Bjorkman, Pamela J.
  • Voorhees, Rebecca M.
  • Clemons, William M.
Defense Date:26 July 2021
Non-Caltech Author Email:michelleyfry (AT)
Record Number:CaltechTHESIS:08232021-203647268
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter 2. adapted for Chapter 4. adapted for Chapter 3. adapted for Chapter 1.
Fry, Michelle Yen0000-0002-3209-5492
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14333
Deposited By: Michelle Fry
Deposited On:27 Aug 2021 19:58
Last Modified:03 May 2022 19:57

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