P4HB

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

P4HB Related Areas

Enzyme>>Other>>P4HB/PDI

P4HB Alternative Names

P4HB, PDI, PDIA1, DSI, ERBA2L, GIT, P4Hbeta, PHDB, PO4DB, PO4HB, PROHB [Homo sapiens]

P4hb, PDI, Pdia1, RP23-84C12.2, ERp59, Thbp [Mus musculus]

Summaries for P4HB

Entrez Gene summary for 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.

OMIM - description for P4HB:

Tasanen et al. (1988) isolated genomic clones for the human gene coding for this multifunctional protein. They found that the gene is about 18 kb long and consists of 11 exons. The codons for the 2 presumed active sites of protein disulfide isomerase, each a cys-gly-his-cys sequence, were found to be located 12 bp from the beginning of exons 2 and 9.

Wikipedia summary for P4HB:

Protein disulfide-isomerase is an enzyme that in humans is encoded by the P4HB gene. 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

Human P4HB Protein General Information

 

• Protein names: Submitted name: P4HB protein
• Sequence length: 273 AA.
• Domain: Redox-active center Repeat Signal
• Sequence similarities: Belongs to the protein disulfide isomerase family. Contains 2 thioredoxin domains.
• Subunit structure: Homodimer. Monomers and homotetramers may also occur. Also constitutes the structural subunit of prolyl 4-hydroxylase and of the microsomal triacylglycerol transfer protein MTTP in mammalian cells. Stabilizes both enzymes and retain them in the ER without contributing to the catalytic activity By similarity. Binds UBQLN1. Binds to CD4, and upon HIV-1 binding to the cell membrane, is part of a P4HB/PDI-CD4-CXCR4-gp120 complex
• Subcellular location: Endoplasmic reticulum lumen. Melanosome. Cell membrane; Peripheral membrane protein Potential. Note: 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. Identified by mass spectrometry in melanosome fractions from stage I to stage IV.

General information above from UniProt

Function for P4HB Protein

UniProtKB:

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

Genatlas:

• P4HB catalyze the rearrangement of -S-S- bonds in proteins
• P4HB has ability to act as a chaperone that inhibits aggregation of misfolded proteins in a concentration-dependent manner, and ability to bind thyroid hormone
• P4HB plays a role in both the influx and efflux of S-nitrosothiol-bound nitric oxide

Homology for human P4HB

• homolog to avian erythroblastic leukemia viral (v-erb-a) oncogene 2