Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The formation of 3-hydroxyproline was studied with crude rat kidney cortex extract as a source of enzyme and chick embryo tendon protocollagen and procollagen or cartilage protocollagen as a substrate. Synthesis of 3-hydroxyproline was observed with all these substrates and the formation of 3-hydroxyproline ranged up to seven residues per pro-alpha-chain. The highest rate of 3-hydroxylation took place at 20 degrees C and the reaction required Fe2+, O2,2-oxoglutarate and ascorbate. The formation of 3-hydroxyproline was affected by chain length and the conformation of the substrate, in that longer polypeptide chains proved better substrates, while the native triple-helical conformation of protocollagen or procollagen completely prevented the reaction. Formation of 3-hydroxyproline with tendon procollagen as a substrate was not inhibited by antiserum to prolyl 4-hydroxylase or by poly(L-proline) when these substances were used in concentrations which clearly inhibited 4-hydroxyproline formation with tendon protocollagen as a substrate. Furthermore, pure prolyl 4-hydroxylase did not synthesize any 3-hydroxyproline under conditions in which the crude rat kidney cortex enzyme would readily do so. The data thus strongly suggest that prolyl 3-hydroxylase and prolyl 4-hydroxylase are separate enzymes.
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PMID:Prolyl 3-hydroxylase: partial characterization of the enzyme from rat kidney cortex. 19 Dec 55

The location of type IV (basement membrane)collagen in early post-implantation mouse embryos was examined by immunoperoxidase reactions using a specific immunoglobulin raised against mouse lens capsule collagen. Reaction was positive in the earliest embryos studied--on the fifth day of gestation (the day of detection of the copulation plug is the first day). It was found only in the primitive endoderm adjacent to the blastocoelic cavity. Subsequently in development, strong staining reactions were found in the parietal endoderm, Reichert's membrane and an acellular layer which separates the visceral endoderm of the egg cylinder from the ectoderm. In tenth to eighteenth day visceral yolk sacs, the mesodermal portion was stained, which is consistent with the presence of basement membranes around blood vessels. The endodermal portion of the visceral yolk sac did not react, while small amounts were found in the amnion. By incubation of various embryonic tissues with tritiated amino acids, purification of the biosynthesized secreted collagens and their partial characterization, the differential expression of several collagen genes was detected. Identification of collagen types was made by: reaction with specific antibodies to type I and IV collagens; electrophoretic mobility; sensitivity to reduction and to collagenase; analysis of the proportions of 3-hydroxyproline, 4-hydroxyproline and hydroxylysine; and CNBr peptides. In agreement with the data of Minor et al. (1976a) for the rat, mouse parietal endoderm synthesizes large amounts of type IV collagen. In contrast to their findings, however, the 165,000 molecular weight polypeptide is not converted to one of 100,000 after reduction, alkylation and repepsinization (Dehm and Kefalides, 1978). The endoderm of the visceral yolk sac was shown to be synthesizing primarily type I collagen, while the mesoderm layer of this membrane synthesized both type I and IV collagens. Little or no type IV collagen synthesis was detected in the endoderm of the visceral yolk sac. If it is correct that the visceral endoderm of the early embryo makes a major contribution to the formation of the endoderm portion of the visceral yolk sac, then it is clear that a switch in collagen gene expression must occur as it does so.
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PMID:The localization and synthesis of some collagen types in developing mouse embryos. 45 57

Prolyl 4-hydroxylase (EC 1.14.11.2), an alpha 2 beta 2 tetramer, catalyzes the posttranslational formation of 4-hydroxyproline in collagens. The enzyme can easily be dissociated into its subunits, but all attempts to associate a tetramer from the dissociated subunits in vitro have been unsuccessful. Molecular cloning of the catalytically important alpha subunit has identified two types of cDNA clone due to mutually exclusive alternative splicing. The beta subunit is a highly unusual multifunctional polypeptide, being identical to the enzyme protein disulfide-isomerase (EC 5.3.4.1). We report here on expression of the alpha and beta subunits of prolyl 4-hydroxylase and a fully active enzyme tetramer in Spodoptera frugiperda insect cells by baculovirus vectors. When the beta subunit was expressed alone, the polypeptide produced was found in a 0.1% Triton X-100 extract of the cell homogenate and was a fully active protein disulfide-isomerase. When either form of the alpha subunit was expressed alone, only traces of the alpha subunit could be extracted from the cell homogenate with 0.1% Triton X-100, and 1% SDS was required to obtain efficient solubilization. These alpha subunits had no prolyl 4-hydroxylase activity. When the cells were coinfected with both alpha- and beta-subunit-producing viruses, an enzyme tetramer was formed, but significant amounts of alpha and beta subunits remained unassociated. The recombinant tetramer was indistinguishable from that isolated from vertebrate tissue in terms of its specific activity and kinetic constants for cosubstrates and the peptide substrate. The two alternatively spliced forms of the alpha subunit gave enzyme tetramers with identical catalytic properties. Baculovirus expression seems to be an excellent system for mass production of the enzyme tetramer and for detailed investigation of the mechanisms involved in the association of the monomers.
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PMID:Characterization of the human prolyl 4-hydroxylase tetramer and its multifunctional protein disulfide-isomerase subunit synthesized in a baculovirus expression system. 132 38

Prolyl 4-hydroxylase, an alpha 2 beta 2 tetramer, catalyzes the formation of 4-hydroxyproline in collagens and related proteins by hydroxylating proline residues in peptide linkages. The beta-subunit of prolyl 4-hydroxylase (P4HB) is a highly unusual multifunctional polypeptide that is identical to the enzyme protein disulfide isomerase and a major cellular thyroid hormone-binding protein and is highly similar to a glycosylation site-binding polypeptide of oligosaccharyl transferase. We report here the regional assignment of the gene for this multifunctional polypeptide. In situ hybridization mapped the gene to 17q25. Southern blot analyses of restricted DNA from a chromosome-mediated gene transfer transfectant panel suggested that the P4HB gene is located distal to the gene for thymidine kinase, either between the genes for thymidine kinase and galactokinase or on the telomeric side of both these genes.
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PMID:Regional assignment of the human gene coding for a multifunctional polypeptide (P4HB) acting as the beta-subunit of prolyl 4-hydroxylase and the enzyme protein disulfide isomerase to 17q25. 164 89

Excessive accumulation of collagen in the extracellular matrix has a crucial role in fibrosis. Thus pharmacological inhibition of collagen deposition is likely to be beneficial for patients suffering from fibrotic disorders such as liver cirrhosis. Prolyl 4-hydroxylase catalyzes the formation of 4-hydroxyproline in collagens and other proteins with collagen-like amino acid sequences by the hydroxylation of proline residues in -X-Pro-Gly- sequences. The reaction products, 4-hydroxyproline residues, serve to stabilize the collagen triple helices under physiological conditions. Conversely, collagen chains that contain no 4-hydroxyproline cannot fold into triple helical molecules that are stable at body temperature. The prolyl 4-hydroxylase reaction therefore seems to be a particularly suitable target for the pharmological regulation of excessive collagen formation. The reaction catalyzed by prolyl 4-hydroxylase requires Fe2+, 2-oxoglutarate, O2 and ascorbate and involves an oxidative decarboxylation of 2-oxoglutarate. The active enzyme is an alpha 2 beta 2 tetramer that consists of two types of inactive monomer and has two catalytic sites. Some parts of the catalytic sites may be built up cooperatively of both the alpha and beta subunits, but the alpha subunit appears to contribute the major part. The beta subunit contains the carboxyl-terminal tetrapeptide sequence -Lys-Asp-Glu-Leu which is essential for the retention of a polypeptide within the lumen of the endoplasmic reticulum. Since the alpha subunit lacks the carboxyl-terminal retention signal, one function of the beta subunit in the prolyl 4-hydroxylase tetramer may be to retain the enzyme within the endoplasmic reticulum.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prolyl 4-hydroxylase and its role in collagen synthesis. 166 65

Structures in four different crystal forms of [Leu1]zervamicin (zervamicin Z-L, Ac-Leu-Ile-Gln-Iva-Ile5-Thr-Aib-Leu-Aib-Hyp10-Gln-Aib-Hyp-Aib-P ro15-Phol, where Iva is isovaline, Aib is alpha-amino isobutyric acid, Hyp is 4-hydroxyproline, and Phol is phenylalaninol), a membrane channel-forming polypeptide from Emericellopsis salmosynnemata, have been determined by x-ray diffraction. The helical structure is amphiphilic with all the polar moieties on the convex side of the bent helix. Helices are bent at Hyp10 from approximately 30 degrees to approximately 45 degrees in the different crystal forms. In all crystal forms, the peptide helices aggregate in a similar fashion to form water channels that are interrupted by hydrogen bonds between N epsilon H(Gln11) and O delta (Hyp10) of adjacent helices. The Gln11 side chain is folded in an unusual fashion in order to close the channel. Space is available for an extended conformation for Gln11, in which case the channel would be open, suggesting a gating mechanism for cation transport. Structural details are presented for one crystal form derived from methanol/water solution: C85H140N18O22. 10H2O, space group P21, a = 23.068(6) A, b = 9.162(3) A, c = 26.727(9) A, beta = 108.69(2) degrees (standard deviation of last digit is given in parentheses); overall agreement factor R = 10.1% for 5322 observed relfections [magnitude of Fo greater than 3 sigma (F)]; resolution, 0.93 A.
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PMID:Crystal structure of [Leu1]zervamicin, a membrane ion-channel peptide: implications for gating mechanisms. 171 Dec 27

The collagens synthesized by Pam cells were biochemically characterized. The collagen in the cell layers was identified as type IV collagen by immunoprecipitation with type IV collagen specific antibody. The apparent molecular weights were 180 Kd and 175 Kd, which converted to major (160 Kd) and several minor smaller fragments with pepsin treatment. The ratios of 3-hydroxyproline/4-hydroxyproline and 4-hydroxyproline/proline in the 160 Kd polypeptide were 0.11 and 1.18, respectively. The result shows that Pam cells are able to produce type IV collagen whose biochemical characteristics are similar to those from other epithelial cells. In the kinetic study, the synthesis of type IV collagen reached its maximum level rapidly on the 1st day after seeding, suggesting that type IV collagen may play a role in cell attachment and proliferation.
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PMID:Type IV collagen synthesis by cultured mouse keratinocytes (Pam cells). 247 Jul 97

Prolyl 4-hydroxylase (EC 1.14.11.2) catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of proline residues in X-Pro-Gly sequences. The reaction requires Fe2+, 2-oxoglutarate, O2, and ascorbate and involves an oxidative decarboxylation of 2-oxoglutarate. Ascorbate is not consumed during most catalytic cycles, but the enzyme also catalyzes decarboxylation of 2-oxoglutarate without subsequent hydroxylation, and ascorbate is required as a specific alternative oxygen acceptor in such uncoupled reaction cycles. A number of compounds inhibit prolyl 4-hydroxylase competitively with respect to some of its cosubstrates or the peptide substrate, and recently many suicide inactivators have also been described. Such inhibitors and inactivators are of considerable interest, because the prolyl 4-hydroxylase reaction would seem a particularly suitable target for chemical regulation of the excessive collagen formation found in patients with various fibrotic diseases. The active prolyl 4-hydroxylase is an alpha 2 beta 2 tetramer, consisting of two different types of inactive monomer and probably containing two catalytic sites per tetramer. The large catalytic site may be cooperatively built up of both the alpha and beta subunits, but the alpha subunit appears to contribute the major part. The beta subunit has been found to be identical to the enzyme protein disulfide isomerase and a major cellular thyroid hormone-binding protein and shows partial homology with a phosphoinositide-specific phospholipase C, thioredoxins, and the estrogen-binding domain of the estrogen receptor. The COOH-terminus of this beta subunit has the amino acid sequence Lys-Asp-Glu-Leu, which was recently suggested to be necessary for the retention of a polypeptide within the lumen of the endoplasmic reticulum. The alpha subunit does not have this COOH-terminal sequence, and thus one function of the beta subunit in the prolyl 4-hydroxylase tetramer appears to be to retain the enzyme within this cell organelle.
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PMID:Protein hydroxylation: prolyl 4-hydroxylase, an enzyme with four cosubstrates and a multifunctional subunit. 253 73

Prolyl 4-hydroxylase [procollagen-proline, 2-oxyglutarate 4-dioxygenase; procollagen-L-proline, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2], an alpha 2 beta 2 tetramer, catalyzes the formation of 4-hydroxyproline in collagens by the hydroxylation of proline residues in peptide linkages. We report here on the isolation of cDNA clones encoding the alpha-subunit of the enzyme from human tumor HT-1080, placenta, and fibroblast cDNA libraries. Eight overlapping clones covering almost all of the corresponding 3000-nucleotide mRNA, including all the coding sequences, were characterized. These clones encode a polypeptide of 517 amino acid residues and a signal peptide of 17 amino acids. Previous characterization of cDNA clones for the beta-subunit of prolyl 4-hydroxylase has indicated that its C terminus has the amino acid sequence Lys-Asp-Glu-Leu, which, it has been suggested, is necessary for the retention of a polypeptide within the lumen of the endoplasmic reticulum. The alpha-subunit does not have this C-terminal sequence, and thus one function of the beta-subunit in the prolyl 4-hydroxylase tetramer appears to be to retain the enzyme within this cell organelle. Interestingly, three of the cDNA clones for the alpha-subunit contained a 64-nucleotide sequence homologous but not identical to the corresponding 64-nucleotide sequence found in four other cDNA clones. Nuclease S1 mapping experiments demonstrated that this difference was due to the existence of two types of mRNA present in approximately equal amounts. Southern blot analyses of human genomic DNA with a cDNA probe for the alpha-subunit suggested the presence of only one gene encoding the two types of mRNA, which appear to result from mutually exclusive alternative splicing of primary transcripts of one gene.
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PMID:Molecular cloning of the alpha-subunit of human prolyl 4-hydroxylase: the complete cDNA-derived amino acid sequence and evidence for alternative splicing of RNA transcripts. 254 75

Preparations of mannose-binding protein isolated from rat liver contain two distinct but homologous polypeptides. The complete primary structures of both of these polypeptides have been determined by sequencing of peptides derived from the proteins, isolation and sequencing of cDNAs for both proteins, and partial characterization of the gene for one of the proteins. Each polypeptide consists of three regions: (a) an NH2-terminal segment of 18-19 amino acids which is rich in cysteine and appears to be involved in the formation of interchain disulfide bonds which stabilize dimeric and trimeric forms of the protein, (b) a collagen-like domain consisting of 18-20 repeats of the sequence Gly-X-Y and containing 4-hydroxyproline residues in several of the Y positions, and (c) a COOH-terminal carbohydrate-binding domain of 148-150 amino acids. The sequences of the COOH-terminal domains are highly homologous to the sequence of the COOH-terminal carbohydrate-recognition portion of the chicken liver receptor for N-acetylglucosamine-terminated glycoproteins and the rat liver asialoglycoprotein receptor. Each protein is preceded by a cleaved, NH2-terminal signal sequence, consistent with the finding that this protein is found in serum as well as in the liver. The entire structure of the mannose-binding proteins is homologous to dog pulmonary surfactant apoprotein.
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PMID:Mannose-binding proteins isolated from rat liver contain carbohydrate-recognition domains linked to collagenous tails. Complete primary structures and homology with pulmonary surfactant apoprotein. 300 80


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