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Prolyl 4-hydroxylase, beta polypeptide
Protein P4HB PDB 1bjx.png
PDB rendering based on 1bjx.
Available structures
PDB Ortholog search: PDBe, RCSB
External IDs OMIM176790 MGI97464 HomoloGene55495 ChEMBL: 5422 GeneCards: P4HB Gene
EC number
RNA expression pattern
PBB GE P4HB 200656 s at tn.png
PBB GE P4HB 200654 at tn.png
More reference expression data
Species Human Mouse
Entrez 5034 18453
Ensembl ENSG00000185624 ENSMUSG00000025130
UniProt P07237 P09103
RefSeq (mRNA) NM_000918 NM_011032
RefSeq (protein) NP_000909 NP_035162
Location (UCSC) Chr 17:
79.8 – 79.82 Mb
Chr 11:
120.56 – 120.57 Mb
PubMed search [1] [2]

Protein disulfide-isomerase is an enzyme that in humans is encoded by the P4HB gene.[1][2][3]

This gene encodes the beta subunit of prolyl 4-hydroxylase, a highly abundant multifunctional enzyme that belongs to the protein disulfide isomerase family. When present as a tetramer consisting of two alpha and two beta subunits, this enzyme is involved in hydroxylation of prolyl residues in preprocollagen. This enzyme is also a disulfide isomerase containing two thioredoxin domains that catalyze the formation, breakage and rearrangement of disulfide bonds. Other known functions include its ability to act as a chaperone that inhibits aggregation of misfolded proteins in a concentration-dependent manner, its ability to bind thyroid hormone, its role in both the influx and efflux of S-nitrosothiol-bound nitric oxide, and its function as a subunit of the microsomal triglyceride transfer protein complex.[2]


P4HB has been shown to interact with UBQLN1,[4] ERO1LB[5][6] and ERO1L.[5][6]


P4HB has become one of a bank of markers considered specific for fibroblasts along with FSP1 and vimentin[7]


  1. ^ Shoulders CC, Brett DJ, Bayliss JD, Narcisi TM, Jarmuz A, Grantham TT, Leoni PR, Bhattacharya S, Pease RJ, Cullen PM, et al. (Mar 1994). "Abetalipoproteinemia is caused by defects of the gene encoding the 97 kDa subunit of a microsomal triglyceride transfer protein". Hum Mol Genet 2 (12): 2109–16. doi:10.1093/hmg/2.12.2109. PMID 8111381. 
  2. ^ a b "Entrez Gene: P4HB procollagen-proline, 2-oxoglutarate 4-dioxygenase (proline 4-hydroxylase), beta polypeptide". 
  3. ^ Galligan JJ, Petersen DR (July 2012). "The human protein disulphide isomerase gene family". Human Genomics 6 (6). doi:10.1186/1479-7364-6-6. 
  4. ^ Ko, Han Seok; Uehara Takashi; Nomura Yasuyuki (Sep 2002). "Role of ubiquilin associated with protein-disulfide isomerase in the endoplasmic reticulum in stress-induced apoptotic cell death". J. Biol. Chem. (United States) 277 (38): 35386–92. doi:10.1074/jbc.M203412200. ISSN 0021-9258. PMID 12095988. 
  5. ^ a b Anelli, Tiziana; Alessio Massimo; Mezghrani Alexandre; Simmen Thomas; Talamo Fabio; Bachi Angela; Sitia Roberto (Feb 2002). "ERp44, a novel endoplasmic reticulum folding assistant of the thioredoxin family". EMBO J. (England) 21 (4): 835–44. doi:10.1093/emboj/21.4.835. ISSN 0261-4189. PMC 125352. PMID 11847130. 
  6. ^ a b Mezghrani, A; Fassio A; Benham A; Simmen T; Braakman I; Sitia R (Nov 2001). "Manipulation of oxidative protein folding and PDI redox state in mammalian cells". EMBO J. (England) 20 (22): 6288–96. doi:10.1093/emboj/20.22.6288. ISSN 0261-4189. PMC 125306. PMID 11707400. 
  7. ^ http://www.antibodies-online.com/news/2/562/Fibroblast+Markers/

Further reading[edit]