Functional characterization of ERp18, a new endoplasmic reticulum-located thioredoxin superfamily member

Alanen, Heli I. and Williamson, Richard A. and Howard, Mark J. and Lappi, Anna-Kaisa and Jantti, Heli P. and Rautio, Sini M. and Kellokumpu, Sakari and Ruddock, Lloyd W. (2003) Functional characterization of ERp18, a new endoplasmic reticulum-located thioredoxin superfamily member. Journal of Biological Chemistry, 278 (31). pp. 28912-28920. ISSN 0021-9258. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Native disulfide bond formation in the endoplasmic reticulum is a critical process in the maturation of many secreted and outer membrane proteins. Although a large number of proteins have been implicated in this process, it is clear that our current understanding is far from complete. Here we describe the functional characterization of a new 18-kDa protein (ERp18) related to protein-disulfide isomerase. We show that ERp18 is located in the endoplasmic reticulum and that it contains a single catalytic domain with an unusual CGAC active site motif and a probable insertion between beta3 and alpha3 of the thioredoxin fold. From circular dichroism and NMR measurements, ERp18 is well structured and undergoes only a minor conformational change upon dithioldisulfide exchange in the active site. Guanidinium chloride denaturation curves indicate that the reduced form of the protein is more stable than the oxidized form, suggesting that it is involved in disulfide bond formation. Furthermore, in vitro ERp18 possesses significant peptide thiol-disulfide oxidase activity, which is dependent on the presence of both active site cysteine residues. This activity differs from that of the human PDI family in that under standard assay conditions it is limited by substrate oxidation and not by enzyme reoxidation. A putative physiological role for Erp18 in native disulfide bond formation is discussed.

Item Type: Article
Additional information: 0021-9258 (Print) Journal Article Research Support, Non-U.S. Gov't
Uncontrolled keywords: Amino Acid Sequence Animals Binding Sites COS Cells Catalysis Circular Dichroism Cysteine Disulfides/metabolism Endoplasmic Reticulum/*chemistry Escherichia coli/genetics Gene Expression Guanidine/chemistry Humans Hydrogen-Ion Concentration Magnetic Resonance Spectroscopy Molecular Sequence Data Oxidation-Reduction Polymerase Chain Reaction Protein Conformation Protein Denaturation Protein Disulfide Reductase (Glutathione) Protein Disulfide-Isomerase/chemistry/genetics/metabolism/*physiology Recombinant Proteins Sequence Alignment Spectrometry, Fluorescence Structure-Activity Relationship Sulfhydryl Compounds/metabolism Thermodynamics *Thioredoxins/genetics Transfection
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Biosciences > Protein Science Group
Depositing User: Richard Williamson
Date Deposited: 09 Sep 2008 03:07
Last Modified: 24 Jun 2014 10:59
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