View source for PDIA3

{{Infobox_gene}}
'''Protein disulfide-isomerase A3''' ('''PDIA3'''), also known as '''glucose-regulated protein, 58-kD''' ('''GRP58'''), is an [[isomerase]] [[enzyme]].<ref name="pmid7487104">{{cite journal | vauthors = Bourdi M, Demady D, Martin JL, Jabbour SK, Martin BM, George JW, Pohl LR | title = cDNA cloning and baculovirus expression of the human liver endoplasmic reticulum P58: characterization as a protein disulfide isomerase isoform, but not as a protease or a carnitine acyltransferase | journal = Archives of Biochemistry and Biophysics | volume = 323 | issue = 2 | pages = 397–403 | date = Nov 1995 | pmid = 7487104 | doi = 10.1006/abbi.1995.0060 }}</ref><ref name="pmid8529662">{{cite journal | vauthors = Hirano N, Shibasaki F, Sakai R, Tanaka T, Nishida J, Yazaki Y, Takenawa T, Hirai H | title = Molecular cloning of the human glucose-regulated protein ERp57/GRP58, a thiol-dependent reductase. Identification of its secretory form and inducible expression by the oncogenic transformation | journal = European Journal of Biochemistry / FEBS | volume = 234 | issue = 1 | pages = 336–42 | date = Nov 1995 | pmid = 8529662 | doi = 10.1111/j.1432-1033.1995.336_c.x }}</ref><ref name="pmid8687406">{{cite journal | vauthors = Koivunen P, Helaakoski T, Annunen P, Veijola J, Räisänen S, Pihlajaniemi T, Kivirikko KI | title = ERp60 does not substitute for protein disulphide isomerase as the beta-subunit of prolyl 4-hydroxylase | journal = The Biochemical Journal | volume = 316 | issue =  2| pages = 599–605 | date = Jun 1996 | pmid = 8687406 | pmc = 1217390 | doi =  10.1042/bj3160599| url = http://www.biochemj.org/bj/316/0599/bj3160599.htm | series = 316 }}</ref> This protein [[subcellular localization|localizes]] to the [[endoplasmic reticulum]] (ER) and interacts with [[lectin]] [[chaperone (protein)|chaperone]]s [[calreticulin]] and [[calnexin]] (CNX) to modulate folding of newly synthesized glycoproteins. It is thought that complexes of lectins and this protein mediate protein folding by promoting formation of disulfide bonds in their glycoprotein substrates.<ref name="entrez">{{cite web | title = Entrez Gene: PDIA3 protein disulfide isomerase family A, member 3| url = https://www.ncbi.nlm.nih.gov/gene/2923| accessdate = }}</ref>

== Structure ==

The PDIA3 protein consists of four thioredoxin-like domains: a, b, b′, and a′. The a and a′ domains have Cys-Gly-His-Cys [[active site]] motifs (C57-G58-H59-C60 and C406-G407-H408-C409) and are catalytically active.<ref name=pmid19119025>{{cite journal | vauthors = Dong G, Wearsch PA, Peaper DR, Cresswell P, Reinisch KM | title = Insights into MHC class I peptide loading from the structure of the tapasin-ERp57 thiol oxidoreductase heterodimer | journal = Immunity | volume = 30 | issue = 1 | pages = 21–32 | date = Jan 2009 | pmid = 19119025 | doi = 10.1016/j.immuni.2008.10.018 | pmc=2650231}}</ref><ref name=pmid16905107>{{cite journal | vauthors = Kozlov G, Maattanen P, Schrag JD, Pollock S, Cygler M, Nagar B, Thomas DY, Gehring K | title = Crystal structure of the bb' domains of the protein disulfide isomerase ERp57 | journal = Structure | volume = 14 | issue = 8 | pages = 1331–9 | date = Aug 2006 | pmid = 16905107 | doi = 10.1016/j.str.2006.06.019 }}</ref> The bb′ domains contain a CNX binding site, which is composed of positively charged, highly conserved residues (K214, K274, and R282) that interact with the negatively charged residues of the CNX P domain. The b′ domain comprises the majority of the binding site, but the β4-β5 loop of the b domain provides additional contact (K214) to strengthen the interaction.<ref name=pmid16905107/> A transient [[disulfide bond]] forms between the [[N-terminal]] cysteine in the catalytic motif and a substrate, but in a step called "escape pathway", the bond is disrupted as the [[C-terminal]] cysteine attacks the N-terminal cysteine to release the substrate.<ref name=pmid19119025/>

== Function ==

The PDIA3 protein is a [[thiol]] [[oxidoreductase]] that has [[protein disulfide isomerase]] activity.<ref name="pmid8687406"/><ref name=pmid19119025/> PDIA3 is also part of the [[major histocompatibility complex]] (MHC) class I [[peptide loading complex]], which is essential for formation of the final antigen conformation and export from the [[endoplasmic reticulum]] to the cell surface.<ref name=pmid19119025/><ref name="pmid16311600">{{cite journal | vauthors = Garbi N, Tanaka S, Momburg F, Hämmerling GJ | title = Impaired assembly of the major histocompatibility complex class I peptide-loading complex in mice deficient in the oxidoreductase ERp57 | journal = Nature Immunology | volume = 7 | issue = 1 | pages = 93–102 | date = Jan 2006 | pmid = 16311600 | doi = 10.1038/ni1288 }}</ref> This protein of the endoplasmic reticulum interacts with lectin chaperones such as calreticulin and CNX in order to modulate the folding of proteins that are newly synthesized. It is believed that PDIA3 plays a role in protein folding by promoting the formation of disulfide bonds, and that CNX facilitates the positioning substrates next to the catalytic cysteines.<ref name="entrez"/><ref name=pmid19119025/> This function allows it to serve as a redox sensor by activating mTORC1, which then mediates mTOR complex assembly to adapt cells to oxidative damage. Thus, PDIA3 regulates [[cell growth]] and [[apoptosis|death]] according to oxygen concentrations, such as in the [[hypoxia (medical)|hypoxic]] microenvironment of bones. Additionally, PDIA3 activates cell [[anchorage]] in bones by associating with [[cell division]] and [[cytoskeleton]] proteins, such as beta-[[actin]] and [[vimentin]], to form a complex which controls [[TUBB3]] folding and proper attachment of the [[microtubule]]s to the [[kinetochore]]. PDIA3 also plays a role in [[cytokine]]-dependent [[signal transduction]], including [[STAT3]] signaling.<ref name=pmid23625662>{{cite journal | vauthors = Santana-Codina N, Carretero R, Sanz-Pamplona R, Cabrera T, Guney E, Oliva B, Clezardin P, Olarte OE, Loza-Alvarez P, Méndez-Lucas A, Perales JC, Sierra A | title = A transcriptome-proteome integrated network identifies endoplasmic reticulum thiol oxidoreductase (ERp57) as a hub that mediates bone metastasis | journal = Molecular & Cellular Proteomics | volume = 12 | issue = 8 | pages = 2111–25 | date = Aug 2013 | pmid = 23625662 | doi = 10.1074/mcp.M112.022772 | pmc=3734573}}</ref>

== Clinical significance ==

It has been demonstrated that the downregulation of ERp57 expression is correlated with poor prognosis in early-stage cervical [[cancer]].<ref>{{cite journal | vauthors = Chung H, Cho H, Perry C, Song J, Ylaya K, Lee H, Kim JH | title = Downregulation of ERp57 expression is associated with poor prognosis in early-stage cervical cancer | journal = Biomarkers | volume = 18 | issue = 7 | date = Nov 2013 | pmid = 23957851 | doi = 10.3109/1354750X.2013.827742 | pages=573–9}}</ref> It has also been demonstrated that ERp57/PDIA3 binds specific DNA fragments in a melanoma cell line.<ref>{{cite journal | vauthors = Aureli C, Gaucci E, Arcangeli V, Grillo C, Eufemi M, Chichiarelli S | title = ERp57/PDIA3 binds specific DNA fragments in a melanoma cell line | journal = Gene | volume = 524 | issue = 2 | date = Jul 2013 | pmid = 23587917 | doi = 10.1016/j.gene.2013.04.004 | pages=390–5}}</ref> PDIA3 is also involved in bone [[metastasis]], which is the most common source of distant relapse in [[breast cancer]].<ref name=pmid23625662/> In addition to cancer, overexpression of PDIA3 is linked to [[renal fibrosis]], which is characterized by excess synthesis and secretion of [[Extracellular matrix|ECM]] leading to ER stress.<ref>{{cite journal | vauthors = Dihazi H, Dihazi GH, Bibi A, Eltoweissy M, Mueller CA, Asif AR, Rubel D, Vasko R, Mueller GA | title = Secretion of ERP57 is important for extracellular matrix accumulation and progression of renal fibrosis, and is an early sign of disease onset | journal = Journal of Cell Science | volume = 126 | issue = Pt 16 | pages = 3649–63 | date = Aug 2013 | pmid = 23781031 | doi = 10.1242/jcs.125088 }}</ref>

== Interactions ==

It has been demonstrated that PDIA3 interacts with: 
*[[BACE1]],<ref name=pmid12052826>{{cite journal | vauthors = Leach MR, Cohen-Doyle MF, Thomas DY, Williams DB | title = Localization of the lectin, ERp57 binding, and polypeptide binding sites of calnexin and calreticulin | journal = The Journal of Biological Chemistry | volume = 277 | issue = 33 | date = Aug 2002 | pmid = 12052826 | doi = 10.1074/jbc.M202405200 | pages=29686–97}}</ref> 
*[[ERP27]],<ref>{{cite journal | vauthors = Alanen HI, Williamson RA, Howard MJ, Hatahet FS, Salo KE, Kauppila A, Kellokumpu S, Ruddock LW | title = ERp27, a new non-catalytic endoplasmic reticulum-located human protein disulfide isomerase family member, interacts with ERp57 | journal = The Journal of Biological Chemistry | volume = 281 | issue = 44 | pages = 33727–38 | date = Nov 2006 | pmid = 16940051 | doi = 10.1074/jbc.M604314200 }}</ref>
*[[tapasin]],<ref name=pmid12052826/><ref name=pmid16905107/>
*[[CALR|CRT]],<ref name=pmid12052826/> and 
*[[CANX|CNX]].<ref name=pmid19119025/><ref name=pmid12052826/><ref name=pmid16905107/>

== See also ==
* [[Antigen processing]] 
* [[Major histocompatibility complex]]

== References ==
{{Reflist|2}}

== External links ==
* {{MeshName|PDIA3+protein,+human}}

{{Intramolecular oxidoreductases}}
{{Enzymes}}
{{Portal bar|Molecular and Cellular Biology|border=no}}

[[Category:EC 5.3.4]]
[[Category:Molecular chaperones]]