Dihydropteridine reductase (QDPR)
The protein contains 244 amino acids for an estimated molecular weight of 25790 Da.
The product of this enzyme, tetrahydrobiopterin (BH-4), is an essential cofactor for phenylalanine, tyrosine, and tryptophan hydroxylases. (updated: April 1, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
Biological Process
Cellular amino acid metabolic process
Cellular nitrogen compound metabolic process
Cellular response to drug
Dihydrobiopterin metabolic process
L-phenylalanine catabolic process
L-phenylalanine metabolic process
Liver development
Response to aluminum ion
Response to glucagon
Response to lead ion
Small molecule metabolic process
Tetrahydrobiopterin biosynthetic process
The reference OMIM entry for this protein is 261630
Hyperphenylalaninemia, bh4-deficient, c; hpabh4c
Hyperphenylalaninemia, tetrahydrobiopterin-deficient, due to dhpr deficiency
Dihydropteridine reductase deficiency
Dhpr deficiency
Quinoid dihydropteridine reductase deficiency
Qdpr deficienc
A number sign (#) is used with this entry because tetrahydrobiopterin (BH4)-deficient hyperphenylalaninemia (HPA) due to dihydropteridine reductase deficiency (HPABH4C) is caused by mutation in the QDPR gene (612676), which encodes an enzyme involved in the salvage pathway for BH4. For a general phenotypic description and a discussion of genetic heterogeneity of BH4-deficient hyperphenylalaninemia, see HPABH4A (261640).
CLINICAL FEATURES
Smith et al. (1975) described 3 children, 2 of them sibs, with an unusual type of phenylketonuria. All 3 (2 of them observed from the neonatal period) had a progressive neurologic illness that did not respond to a low phenylalanine diet, unlike classic PKU (261600). The biochemical features suggested that the block in conversion of phenylalanine to tyrosine was less severe than in classic PKU. Phenylalanine hydroxylase (PAH; 612349), measured in 1 patient, was normal. Smith et al. (1975) suggested that the patients had a disorder of biopterin metabolism possibly due to a defect in the enzyme dihydropteridine reductase. Butler et al. (1975) reported dihydropteridine reductase deficiency in a patient unresponsive to dietary treatment. Biopterin is the natural cofactor for phenylalanine hydroxylase. In its active tetra-hydro form (BH4), biopterin donates hydrogen ions during the hydroxylation reaction. The same cofactor system is active in neural tissue for hydroxylation of tyrosine to dihydroxyphenylalanine (levodopa) in the synthesis of amine transmitters (dopaminine, noradrenaline, and adrenaline) and serotonin. Phenylalanine restriction would not be expected to help the neurologic problem. Basal ganglion symptoms can be related to the importance of levodopa and dopamine to that part of the brain. Kaufman et al. (1975) demonstrated absence of dihydropteridine reductase in liver, brain, and cultured skin fibroblasts of a patient with elevated blood phenylalanine and no response to diet despite good control of blood levels. Watts et al. (1979) reported a patient with hyperphenylalaninemia who had better tolerance of phenylalanine compared to patients with classic PKU. However, unlike patients with classic PKU, treatment with trimethoprim reduced the phenylalanine tolerance in this patient. Since trimethoprim inhibits 7,8-dihydrobiopterin reduction, Watts et al. (1979) speculated that the causative defect may involve the gene for dihydropteridine reductase such that it is sensitive to the reduced availability of tetrahydrobiopterin produced by trimethoprim. Woody et al. (1989) pointed out that without folinic acid therapy as a source of tetrahydrofolate, patients with DHPR deficiency show progressive basal ganglia and other subcortical calcification. The pattern of calcification resembled that seen in CNS folate deficiency, both that in the congenital form (229050) and that in the methotrexate-induced form. Larnaout et al. (1998) described 2 brothers with juvenile-onset DHPR deficiency. Both were considered normal until 6 years of age when they developed a fluctuating and progressive encephalopathy combining mental retardation, epilepsy, and pyramidal, cerebellar, and extrapyramidal signs.DIAGNOSIS
- Prenatal Diagnosis Dahl et al. (1987, 1988) showed that RFLPs of the DHPR locus could be used for prenatal diagnosis.CLINICAL MANAGEMENT
Danks et al. (1975) found that intravenous tetrahydrobiopterin (BH4) treatment was effective and resulted in a fall in serum phenylalanine. ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 261630 was added.
Jan. 28, 2016: Protein entry updated
Automatic update: model status changed
Jan. 24, 2016: Protein entry updated
Automatic update: model status changed