P4HB - Protein disulfide-isomerase - human protein (Function)
 
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P4HB »  Protein disulfide-isomerase   [ EC 5.3.4.1 ]  (PDI)
 
Protein also known as:  Cellular thyroid hormone-binding protein.
Gene name:  P4HB
Entry whose protein(s) existence is based on evidence at protein level
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GENE REF ISO

Function

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Overview 
This multifunctional protein catalyzes the formation, breakage and rearrangement of disulfide bonds. At the cell surface, seems to act as a reductase that cleaves disulfide bonds of proteins attached to the cell. May therefore cause structural modifications of exofacial proteins. Inside the cell, seems to form/rearrange disulfide bonds of nascent proteins. At high concentrations, functions as a chaperone that inhibits aggregation of misfolded proteins. At low concentrations, facilitates aggregation (anti-chaperone activity). May be involved with other chaperones in the structural modification of the TG precursor in hormone biogenesis. Also acts a structural subunit of various enzymes such as prolyl 4-hydroxylase and microsomal triacylglycerol transfer protein MTTP.  
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  • CuratedUniProtKB
GO molecular function 
Poly(A) RNA bindingdefinition[GO:0044822]  
2
  • IDAUniProtKB
Contributes to procollagen-proline 4-dioxygenase activitydefinition[GO:0004656]  
1
  • IDAMGI
Protein bindingdefinition[GO:0005515]  
5
  • IPIIntAct
  • IPIBHF-UCL
Protein disulfide isomerase activitydefinition[GO:0003756] silver  
  • IBARefGenome
Protein disulfide oxidoreductase activitydefinition[GO:0015035] silver  
  • IEAInterPro 2 GO
Protein heterodimerization activitydefinition[GO:0046982] silver  
  • IEAOrtholog Compara
GO biological process 
Cell redox homeostasisdefinition[GO:0045454] silver  
  • IEAInterPro 2 GO
Cellular response to hypoxiadefinition[GO:0071456]  
1
  • IMPBHF-UCL
Glycerol ether metabolic processdefinition[GO:0006662] silver  
  • IEAInterPro 2 GO
Peptidyl-proline hydroxylation to 4-hydroxy-L-prolinedefinition[GO:0018401]  
1
  • IDAMGI
Protein foldingdefinition[GO:0006457] silver  
  • IBARefGenome
Regulation of intrinsic apoptotic signaling pathway in response to oxidative stressdefinition[GO:1902175]  
1
  • IMPBHF-UCL
Response to endoplasmic reticulum stressdefinition[GO:0034976]  
1
  • IMPBHF-UCL
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC 5.3.4.1: Catalyzes the rearrangement of -S-S- bonds in proteins.  
  • CuratedUniProtKB
 
More information is available from:
Pathways 
According to KEGG, this protein belongs to the following pathway:
Protein processing in endoplasmic reticulum  hsa04141+5034  
According to Reactome, this protein belongs to the following pathways:
Cellular responses to stress  REACT_120956  
Extracellular matrix organization  REACT_118779  
Metabolism  REACT_111217  
Note 
Reduces and may activate fusogenic properties of HIV-1 gp120 surface protein, thereby enabling HIV-1 entry into the cell.  
  • CuratedUniProtKB
 

Keywords

Molecular function 
Chaperone  definition   [KW-0143]
Isomerase  definition   [KW-0413]
Technical term 
Reference proteome  definition   [KW-1185]
 

Further external links

GeneWiki: P4HB
GenomeRNAi: 5034
PRO: PR:P07237