Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.14.11.2 (prolyl hydroxylase)
 1,814 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A fraction greatly enriched in microsomes was prepared from chick embryo limb bone tissue homogenates by differential centrifugation in a high density solution of Metrizamide. This fraction was used to determine the submicrosomal localization of prolyl hydroxylase. At a low concentration (0.05%) of the non-ionic detergents Triton X-100 and Brij-35, 90 to 93% of prolyl hydroxylase activity was released from microsomes. Concentrations of Triton X-100 greater than 0.1% were required to solubilize the intrinsic membrane enzyme NADH-ferricyanide reductase and to release membrane-bound ribosomes, while Brij-35 did not extensively solubilize membrane components even at concentrations up to 0.4%. In addition, prolyl hydroxylase activity which could subsequently be released from microsomes by Brij-35 was relatively resistant to trypsin proteolysis at concentrations which removed more than 50% of the ribosomes and approximately 40% of the protein from microsomes. These results suggest that 90 to 93% of prolyl hydroxylase activity in connective tissue is located within the cisternae of the endoplasmic reticulum. Gel filtration of prolyl hydroxylase released from microsomes or found in the soluble fraction of limb bone homogenates revealed two peaks of activity corresponding to molecular weights of 230,000 and 450,000 to 500,000. The latter is twice the value reported for purified chick embryo prolyl hydroxylase. A fraction of the total prolyl hydroxylase activity (generally 20 to 35%) in microsome preparations could be measured in the absence of detergent, although the microsomal membrane should be impermeable to the large unhydroxylated collagen chains used as substrate. On the basis of experimental data, it was concluded that detergent-independent activity was most likely due to damaged microsomal membranes and that this damage was sufficient to allow substrate and trypsin to enter the cisternae but not to allow prolyl hydroxylase to be released.
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PMID:Submicrosomal localization of prolyl hydroxylase from chick embryo limb bone. 18 83

Tubers of potato (Solanum tuberosum L.) contain a number of chitin-binding proteins which have possible functions in defence against pathogens. A major protein of the tuber is the chitin-binding lectin which has been further characterized with respect to its antigenicity and N-terminal amino acid sequence. By using an antiserum monospecific for tuber lectin in unwounded potato the protein was found in the cytoplasm and vacuole, unusually for a hydroxyproline-rich glycoprotein, but consistent with its soluble nature in subcellular extracts. Little increased synthesis of the lectin precursor or the post-translationally modified form could be demonstrated in excised potato tuber discs. However, after wounding there is increased synthesis of another hydroxyproline-containing glycoprotein of Mr 57,000, which binds to chitin and shares common epitopes with the lectin. In comparison with the tuber lectin, this novel glycoprotein contains less hydroxyproline, but from its overall composition it is clearly not an underhydroxylated form of the tuber lectin. It differed in its N-terminal amino acid sequence and was much less glycosylated, although arabinose was still present. Synthesis of the Mr-57,000 polypeptide began after the initial burst of protein synthesis and increased, reaching a peak at 24 h after wounding. The protein was produced with its enzymes of post-translational modification, prolyl hydroxylase and arabinosyltransferase, concomitantly with the marker enzymes for wounding, phenylalanine ammonia-lyase and membrane-bound phenol oxidase and peroxidase.
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PMID:Chitin-binding proteins in potato (Solanum tuberosum L.) tuber. Characterization, immunolocalization and effects of wounding. 159 Jul 71

1. Subcellular fractions of freshly isolated matrix-free embryonic chick tendon and sternal cartilage cells have been characterized by chemical analysis, electron microscopy and the location of specific marker enzymes. These data indicate the fractions to be of a high degree of purity comparable with those obtained from other tissues, e.g. liver and kidney. 2. When homogenates were assayed for protocollagen prolyl hydroxylase and protocollagen lysyl hydroxylase activities, addition of Triton X-100 (0.1%, w/v) was found to stimulate enzyme activities by up to 60% suggesting that the enzymes were probably membrane-bound. 3. Assay of subcellular fractions obtained by differential centrifugation for protocollagen prolyl hydroxylase activity indicated the specific activity to be highest in the microsomal fraction. Similar results were obtained for protocollagen lysyl hydroxylase activity. 4. Submicrosomal fractions obtained by discontinuous sucrose-gradient centrifugation were assayed for the two enzymes and protocollagen prolyl hydroxylase and protocollagen lysyl hydroxylase were found to be associated almost exclusively with the rough endoplasmic reticulum fraction in both tendon and cartilage cells.
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PMID:Collagen biosynthesis. Characterization of subcellular fractions from embyonic chick fibroblasts and the intracellular localization of protocollagen prolyl and protocollagen lysyl hydroxylases. 437 55

Polysomes were isolated from calcified and matrix-containing tissues, such as rat calvaria, rat chondrosarcoma and chick embryos. The method of isolation involves preliminary swelling of the tissues in hypotonic buffer containing heparin and cycloheximide. After homogenization, differential centrifugation is used to separate membrane-bound and non-bound polysomes. Each fraction is rehomogenized in the presence of detergent (Triton X-100) and potassium ions (0.25M). Polysomes are harvested by centrifugation through sucrose cushions in the continued presence of high levels of potassium ions and heparin. Total, non-bound, and membrane-bound polysomes prepared in this manner are equally active in protein synthesizing activity in an heterologous cell-free system. The distribution between non-bound and membrane-bound polysomes in the 12 day old chick embryo is 43 and 57 per cent respectively. Sucrose gradient profiles of polypeptide chains on polysomes labeled in organ culture correlate well with the protein synthetic activity of the isolated polysomes. Much of the protein synthetic activity is devoted to collagen. Polysomal fractions obtained from sucrose gradients show preferential incorporation of 3H-proline and nearly 60 per cent of trichloroacetic acid precipitable material is susceptible to collagenase digestion. Products of synthesis are also substrates for collagen specific enzyme, prolyl hydroxylase. The method described in this communication overcomes the inherent difficulties in obtaining active polysomes from calcified and matrix-containing tissues.
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PMID:Isolation and partial characterization of active polysomes from calcified and matrix-containing tissues. 627 Oct 84

Recently, complex O-glycosylation of the cytoplasmic/nuclear protein Skp1 has been characterized in the eukaryotic microorganism Dictyostelium. Skp1's glycosylation is mediated by the sequential action of a prolyl hydroxylase and five conventional sugar nucleotide-dependent glycosyltransferase activities that reside in the cytoplasm rather than the secretory compartment. The Skp1-HyPro GlcNAcTransferase, which adds the first sugar, appears to be related to a lineage of enzymes that originated in the prokaryotic cytoplasm and initiates mucin-type O-linked glycosylation in the lumen of the eukaryotic Golgi apparatus. GlcNAc is extended by a bifunctional glycosyltransferase that mediates the ordered addition of beta1,3-linked Gal and alpha1,2-linked Fuc. The architecture of this enzyme resembles that of certain two-domain prokaryotic glycosyltransferases. The catalytic domains are related to those of a large family of prokaryotic and eukaryotic, cytoplasmic, membrane-bound, inverting glycosyltransferases that modify glycolipids and polysaccharides prior to their translocation across membranes toward the secretory pathway or the cell exterior. The existence of these enzymes in the eukaryotic cytoplasm away from membranes and their ability to modify protein acceptors expose a new set of cytoplasmic and nuclear proteins to potential prolyl hydroxylation and complex O-linked glycosylation.
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PMID:Complex glycosylation of Skp1 in Dictyostelium: implications for the modification of other eukaryotic cytoplasmic and nuclear proteins. 1188 37

Sre1, the fission yeast sterol regulatory element binding protein, is an endoplasmic reticulum membrane-bound transcription factor that responds to changes in oxygen-dependent sterol synthesis as an indirect measure of oxygen availability. Under low oxygen, Sre1 is proteolytically cleaved and the released N-terminal transcription factor (Sre1N) activates gene expression essential for hypoxic growth. Here, we describe an oxygen-dependent mechanism for regulation of Sre1 that is independent of sterol-regulated proteolysis. Using yeast expressing only Sre1N, we show that Sre1N turnover is regulated by oxygen. Ofd1, an uncharacterized prolyl 4-hydroxylase-like 2-oxoglutarate-Fe(II) dioxygenase, accelerates Sre1N degradation in the presence of oxygen. However, unlike the prolyl 4-hydroxylases that regulate mammalian hypoxia-inducible factor, Ofd1 uses multiple domains to regulate Sre1N degradation by oxygen; the Ofd1 N-terminal dioxygenase domain is required for oxygen sensing and the Ofd1 C-terminal domain accelerates Sre1N degradation. Our data support a model whereby the Ofd1 N-terminal dioxygenase domain is an oxygen sensor that regulates the activity of the C-terminal degradation domain.
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PMID:Oxygen-regulated degradation of fission yeast SREBP by Ofd1, a prolyl hydroxylase family member. 1841 81

We present clinical, radiological, biochemical, and genetic findings on six patients from two consanguineous families that show EDS-like features and radiological findings of a mild skeletal dysplasia. The EDS-like findings comprise hyperelastic, thin, and bruisable skin, hypermobility of the small joints with a tendency to contractures, protuberant eyes with bluish sclerae, hands with finely wrinkled palms, atrophy of the thenar muscles, and tapering fingers. The skeletal dysplasia comprises platyspondyly with moderate short stature, osteopenia, and widened metaphyses. Patients have an increased ratio of total urinary pyridinolines, lysyl pyridinoline/hydroxylysyl pyridinoline (LP/HP), of approximately 1 as opposed to approximately 6 in EDS VI or approximately 0.2 in controls. Lysyl and prolyl residues of collagens were underhydroxylated despite normal lysyl hydroxylase and prolyl 4-hydroxylase activities; underhydroxylation was a generalized process as shown by mass spectrometry of the alpha1(I)- and alpha2(I)-chain-derived peptides of collagen type I and involved at least collagen types I and II. A genome-wide SNP scan and sequence analyses identified in all patients a homozygous c.483_491 del9 SLC39A13 mutation that encodes for a membrane-bound zinc transporter SLC39A13. We hypothesize that an increased Zn(2+) content inside the endoplasmic reticulum competes with Fe(2+), a cofactor that is necessary for hydroxylation of lysyl and prolyl residues, and thus explains the biochemical findings. These data suggest an entity that we have designated "spondylocheiro dysplastic form of EDS (SCD-EDS)" to indicate a generalized skeletal dysplasia involving mainly the spine (spondylo) and striking clinical abnormalities of the hands (cheiro) in addition to the EDS-like features.
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PMID:Spondylocheiro dysplastic form of the Ehlers-Danlos syndrome--an autosomal-recessive entity caused by mutations in the zinc transporter gene SLC39A13. 1851 83

Sre1, the fission yeast sterol regulatory element-binding protein, is an ER membrane-bound transcription factor that controls adaptation to low oxygen growth. Under low oxygen, Sre1 is proteolytically cleaved and the N-terminal transcription factor domain (Sre1N) is released from the membrane and enters the nucleus to activate hypoxic gene expression. Ofd1, a prolyl 4-hydroxylase-like 2-oxoglutarate dioxygenase, controls the oxygen-dependent stability of Sre1N. In the presence of oxygen, Ofd1 accelerates the degradation of Sre1N, but under low oxygen Ofd1 is inhibited and Sre1N accumulates. To identify the regulators of Sre1N, we performed a plasmid-based screen for genes that increased Sre1N transcriptional activity. Here, we identify Nro1 (SPCC4B3.07) as a positive regulator of Sre1N stability and a direct inhibitor of Ofd1. In the absence of oxygen, Nro1 binds to the Ofd1 C-terminal degradation domain and inhibits Sre1N degradation. In the presence of oxygen, Nro1 binding to Ofd1 is disrupted, leading to rapid degradation of Sre1N. We conclude that the Ofd1 dioxygenase domain functions as an oxygen sensor that regulates binding of Nro1 to Ofd1 to control oxygen-dependent Sre1N stability.
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PMID:Oxygen-dependent binding of Nro1 to the prolyl hydroxylase Ofd1 regulates SREBP degradation in yeast. 1915 63

The enzyme prolyl hydroxylase which is responsible for the hydroxylation of peptidyl proline has been investigated in extracts of maize roots. The optimum conditions under which this enzyme can be assayed have been determined using both a colorometric and a radiochemical assay. The enzyme has certain features in common with vertebrate prolyl hydroxylase (pH optimum, requirement for ferrous ion, inhibition by tricine and phosphate buffers, stimulation by bovine serum albumin) but prefers poly-L-proline to collagenous substrates. Centrifugation studies shows that the enzyme is mainly membrane-bound and is primarily localized in the endoplasmic reticulum, although the presence of small amounts in the Golgi apparatus cannot be ruled out.
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PMID:Intracellular localization of posttranslational modifications in the synthesis of hydroxyproline-rich glycoproteins. Peptidyl proline hydroxylation in maize roots. 2424 73

Pulmonary neuroepithelial bodies (NEBs), presumed polymodal airway sensors, consist of innervated clusters of amine (serotonin) and peptide-producing cells. While NEB responses to acute hypoxia are mediated by a membrane-bound O2 sensor complex, responses to sustained and/or chronic hypoxia involve a prolyl hydroxylase (PHD)-hypoxia-inducible factor-dependent mechanism. We have previously reported hyperplasia of NEBs in the lungs of Phd1-/- mice associated with enhanced serotonin secretion. Here we use a novel multilabel immunofluorescence method to assess NEB distribution, frequency, and size, together with the number and size of NEB cell nuclei, and to colocalize multiple cytoplasmic and nuclear epitopes in the lungs of Phd1-/-, Phd2+/-, and Phd3-/- mice and compare them with wild-type controls. To define the mechanisms of NEB cell hyperplasia, we used antibodies against Mash1 and Prox1 (neurogenic genes involved in NEB cell differentiation/maturation), hypoxia-inducible factor-1alpha, and the cell proliferation marker Ki67. Morphometric analysis of (% total lung area) immunostaining for synaptophysin (% synaptophysin), a cytoplasmic marker of NEB cells, was significantly increased in Phd1-/- and Phd3-/- mice compared to wild-type mice. In addition, NEB size and the number and size of NEB nuclei were also significantly increased, indicating that deficiency of Phds is associated with striking hyperplasia and hypertrophy of NEBs. In Phd2+/- mice, while mean % synaptophysin was comparable to wild-type controls, the NEB size was moderately increased, suggesting an effect even in heterozygotes. NEBs in all Phd-deficient mice showed increased expression of Mash1, Prox1, Ki67, and hypoxia-inducible factor-1alpha, in keeping with enhanced differentiation from precursor cells and a minor component of cell proliferation. Since the loss of PHD activity mimics chronic hypoxia, our data provide critical information on the potential role of PHDs in the pathobiology and mechanisms of NEB cell hyperplasia that is relevant to a number of pediatric lung disorders.
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PMID:Hyperplasia and hypertrophy of pulmonary neuroepithelial bodies, presumed airway hypoxia sensors, in hypoxia-inducible factor prolyl hydroxylase-deficient mice. 2780 May 9


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