Affordable Access

deepdyve-link
Publisher Website

Topogenesis and cell surface trafficking of GPR34 are facilitated by positive-inside rule that effects through a tri-basic motif in the first intracellular loop.

Authors
  • Hasegawa, Haruki1
  • Patel, Neha2
  • Ettehadieh, Elham2
  • Li, Peng2
  • Lim, Ai Ching2
  • 1 Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA 94080, USA. Electronic address: [email protected]
  • 2 Department of Therapeutic Discovery, Amgen Inc., South San Francisco, CA 94080, USA.
Type
Published Article
Journal
Biochimica et Biophysica Acta
Publisher
Elsevier
Publication Date
Jul 01, 2016
Volume
1863
Issue
7 Pt A
Pages
1534–1551
Identifiers
DOI: 10.1016/j.bbamcr.2016.04.010
PMID: 27086875
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Protein folding, topogenesis and intracellular targeting of G protein-coupled receptors (GPCRs) must be precisely coordinated to ensure correct receptor localization. To elucidate how different steps of GPCR biosynthesis work together, we investigated the process of membrane topology determination and how it relates to the acquisition of cell surface trafficking competence in human GPR34. By monitoring a fused FLAG-tag and a conformation-sensitive native epitope during the expression of GPR34 mutant panel, a tri-basic motif in the first intracellular loop was identified as the key topogenic signal that dictates the orientation of transmembrane domain-1 (TM1). Charge disruption of the motif perturbed topogenic processes and resulted in the conformational epitope loss, post-translational processing alteration, and trafficking arrest in the Golgi. The placement of a cleavable N-terminal signal sequence as a surrogate topogenic determinant overcame the effects of tri-basic motif mutations and rectified the TM1 orientation; thereby restored the conformational epitope, post-translational modifications, and cell surface trafficking altogether. Progressive N-tail truncation and site-directed mutagenesis revealed that a proline-rich segment of the N-tail and all four cysteines individually located in the four separate extracellular regions must simultaneously reside in the ER lumen to muster the conformational epitope. Oxidation of all four cysteines was necessary for the epitope formation, but the cysteine residues themselves were not required for the trafficking event. The underlying biochemical properties of the conformational epitope was therefore the key to understand mechanistic processes propelled by positive-inside rule that simultaneously regulate the topogenesis and intracellular trafficking of GPR34. Copyright © 2016 Amgen Inc. Published by Elsevier B.V. All rights reserved.

Report this publication

Statistics

Seen <100 times