P4HB

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. [provided by RefSeq, Jul 2008]

Full Name

Prolyl 4-Hydroxylase Subunit Beta

Function

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. Receptor for LGALS9; the interaction retains P4HB at the cell surface of Th2 T helper cells, increasing disulfide reductase activity at the plasma membrane, altering the plasma membrane redox state and enhancing cell migration (PubMed:21670307).

Biological Process

Cellular response to hypoxiaManual Assertion Based On ExperimentIMP:BHF-UCL
Cellular response to interleukin-7IEA:Ensembl
Interleukin-12-mediated signaling pathwayTAS:Reactome
Interleukin-23-mediated signaling pathwayTAS:Reactome
Peptidyl-proline hydroxylation to 4-hydroxy-L-prolineManual Assertion Based On ExperimentIDA:MGI
Positive regulation of cell adhesionManual Assertion Based On ExperimentIMP:ARUK-UCL
Positive regulation of substrate adhesion-dependent cell spreadingManual Assertion Based On ExperimentIMP:ARUK-UCL
Positive regulation of viral entry into host cellManual Assertion Based On ExperimentIMP:UniProtKB
Protein foldingManual Assertion Based On ExperimentIBA:GO_Central
Protein folding in endoplasmic reticulumManual Assertion Based On ExperimentIDA:FlyBase
Regulation of oxidative stress-induced intrinsic apoptotic signaling pathwayManual Assertion Based On ExperimentIMP:BHF-UCL
Response to endoplasmic reticulum stressManual Assertion Based On ExperimentIMP:BHF-UCL

Cellular Location

Endoplasmic reticulum
Endoplasmic reticulum lumen
Melanosome
Cell membrane
Highly abundant. In some cell types, seems to be also secreted or associated with the plasma membrane, where it undergoes constant shedding and replacement from intracellular sources (Probable). Localizes near CD4-enriched regions on lymphoid cell surfaces (PubMed:11181151).
Identified by mass spectrometry in melanosome fractions from stage I to stage IV (PubMed:10636893).
Colocalizes with MTTP in the endoplasmic reticulum (PubMed:23475612).

Involvement in disease

Cole-Carpenter syndrome 1 (CLCRP1):
A form of Cole-Carpenter syndrome, a disorder characterized by features of osteogenesis imperfecta such as bone deformities and severe bone fragility with frequent fractures, in association with craniosynostosis, ocular proptosis, hydrocephalus, growth failure and distinctive facial features. Craniofacial findings include marked frontal bossing, midface hypoplasia, and micrognathia. Despite the craniosynostosis and hydrocephalus, intellectual development is normal. CLCRP1 inheritance is autosomal dominant.