Identification of a novel endoplasmic reticulum export motif within the eighth alpha-helical domain (alpha-H8) of the human prostacyclin receptor

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Title: Identification of a novel endoplasmic reticulum export motif within the eighth alpha-helical domain (alpha-H8) of the human prostacyclin receptor
Authors: Donnellan, Peter D.
Kimbembe, Cisca C.
Reid, Helen M.
Kinsella, B. Therese
Permanent link: http://hdl.handle.net/10197/3165
Date: Apr-2011
Abstract: The human prostacyclin receptor (hIP) undergoes agonist-dependent trafficking involving a direct interaction with Rab11a GTPase. The region of interaction was localised to a 14 residue Rab11a binding domain (RBD) within the proximal carboxyl-terminal (C)-tail domain of the hIP, consisting of Val299 – Val307 within the eighth helical domain (alpha-H8) adjacent to the palmitoylated residues at Cys308 – Cys311. However, the factors determining the anterograde transport of the newly synthesised hIP from the endoplasmic reticulum (ER) to the plasma membrane (PM) have not been identified. The aim of the current study was to identify the major ER export motif(s) within the hIP initially by investigating the role of Lys residues in its maturation and processing. Through site-directed and Ala-scanning mutational studies in combination with analyses of protein expression and maturation, functional analyses of ligand binding, agonist-induced intracellular signalling and confocal image analyses, it was determined that Lys297, Arg302 and Lys304 located within alpha-H8 represent the critical determinants of a novel ER export motif of the hIP. Furthermore, while substitution of those critical residues significantly impaired maturation and processing of the hIP, replacement of the positively charged Lys with Arg residues, and vice versa, was functionally permissible. Hence, this study has identified a novel 8 residue ER export motif within the functionally important alpha-H8 of the hIP. This ER export motif, defined by ‘K/R(X)4K/R(X)K/R’, has a strict requirement for positively charged, basic Lys/Arg residues at the 1st, 6th and 8th positions and appears to be evolutionarily conserved within IP sequences from mouse to man.
Funding Details: Science Foundation Ireland
Health Research Board
Type of material: Journal Article
Publisher: Elsevier
Copyright (published version): 2011 Elsevier B.V.
Keywords: Prostacyclin receptor;Alpha helix 8;GPCR;Endoplasmic reticulum;Trafficking;Export
Subject LCSH: G proteins
Prostacyclin--Receptors
Endoplasmic reticulum
DOI: 10.1016/j.bbamem.2011.01.003.
Language: en
Status of Item: Peer reviewed
Appears in Collections:Conway Institute Research Collection
Biomolecular and Biomedical Science Research Collection

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