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The Biochemical Journal Nov 1972
Topics: Chromatography, Gel; Chromatography, Ion Exchange; Hemolysis; Insulin; Iodine Isotopes; Monoiodotyrosine
PubMed: 4655439
DOI: 10.1042/bj1300321 -
The New England Journal of Medicine Apr 2008DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis. We screened...
DEHAL1 has been identified as the gene encoding iodotyrosine deiodinase in the thyroid, where it controls the reuse of iodide for thyroid hormone synthesis. We screened patients with hypothyroidism who had features suggestive of an iodotyrosine deiodinase defect for mutations in DEHAL1. Two missense mutations and a deletion of three base pairs were identified in four patients from three unrelated families; all the patients had a dramatic reduction of in vitro activity of iodotyrosine deiodinase. Patients had severe goitrous hypothyroidism, which was evident in infancy and childhood. Two patients had cognitive deficits due to late diagnosis and treatment. Thus, mutations in DEHAL1 led to a deficiency in iodotyrosine deiodinase in these patients. Because infants with DEHAL1 defects may have normal thyroid function at birth, they may be missed by neonatal screening programs for congenital hypothyroidism.
Topics: Adult; Amino Acid Sequence; Child; DNA Mutational Analysis; Female; Frameshift Mutation; Goiter; Homozygote; Humans; Hypothyroidism; Iodide Peroxidase; Male; Middle Aged; Molecular Sequence Data; Monoiodotyrosine; Mutation, Missense; Open Reading Frames; Phenotype; Polymerase Chain Reaction; Sequence Deletion
PubMed: 18434651
DOI: 10.1056/NEJMoa0706819 -
International Journal of Molecular... Nov 2013Planaria are the simplest organisms with bilateral symmetry and a central nervous system (CNS) with cephalization; therefore, they could be useful as model organisms to...
Planaria are the simplest organisms with bilateral symmetry and a central nervous system (CNS) with cephalization; therefore, they could be useful as model organisms to investigate mechanistic aspects of parkinsonism and to screen potential therapeutic agents. Taking advantage of the organism's anti-tropism towards light, we measured a significantly reduced locomotor velocity in planaria after exposure to 3-iodo-L-tyrosine, an inhibitor of tyrosine hydroxylase that is an enzyme catalyzing the first and rate-limiting step in the biosynthesis of catecholamines. A simple semi-automatic assay using videotaped experiments and subsequent evaluation by tracking software was also implemented to increase throughput. The dopaminergic regulation of locomotor velocity was confirmed by bromocriptine, a drug whose mechanisms of action to treat Parkinson's disease is believed to be through the stimulation of nerves that control movement.
Topics: Animals; Bromocriptine; Humans; Light; Locomotion; Models, Animal; Monoiodotyrosine; Parkinson Disease; Planarians; Protein Binding; Receptors, Dopamine; Tyrosine 3-Monooxygenase
PubMed: 24287905
DOI: 10.3390/ijms141223289 -
Applied and Environmental Microbiology Mar 2014Synthetic biologists construct complex biological circuits by combinations of various genetic parts. Many genetic parts that are orthogonal to one another and are...
Synthetic biologists construct complex biological circuits by combinations of various genetic parts. Many genetic parts that are orthogonal to one another and are independent of existing cellular processes would be ideal for use in synthetic biology. However, our toolbox is still limited with respect to the bacterium Escherichia coli, which is important for both research and industrial use. The site-specific incorporation of unnatural amino acids is a technique that incorporates unnatural amino acids into proteins using a modified exogenous aminoacyl-tRNA synthetase/tRNA pair that is orthogonal to any native pairs in a host and is independent from other cellular functions. Focusing on the orthogonality and independency that are suitable for the genetic parts, we designed novel AND gate and translational switches using the unnatural amino acid 3-iodo-l-tyrosine incorporation system in E. coli. A translational switch was turned on after addition of 3-iodo-l-tyrosine in the culture medium within minutes and allowed tuning of switchability and translational efficiency. As an application, we also constructed a gene expression system that produced large amounts of proteins under induction conditions and exhibited zero-leakage expression under repression conditions. Similar translational switches are expected to be applicable also for eukaryotes such as yeasts, nematodes, insects, mammalian cells, and plants.
Topics: Escherichia coli; Gene Expression Regulation; Genetic Vectors; Genetics, Microbial; Molecular Biology; Monoiodotyrosine; Protein Biosynthesis
PubMed: 24375139
DOI: 10.1128/AEM.03417-13 -
Blood Sep 1998CD36 is an 88-kD glycoprotein involved in the cytoadherence of Plasmodium falciparum-parasitized erythrocytes (PE) to endothelial cells. The molecular mechanisms...
CD36 is an 88-kD glycoprotein involved in the cytoadherence of Plasmodium falciparum-parasitized erythrocytes (PE) to endothelial cells. The molecular mechanisms involved in CD36-dependent cytoadherence were examined by expressing three CD36 homologues (human, murine, and rat) in COS-7 cells and observing their PE-binding characteristics over a pH range of 6.0 to 7.4 and following iodination of these receptors. PE binding to human CD36 was pH dependent, with peak binding at pH 6.8 to 7.0, and binding was unaffected by iodination. In contrast, PE adherence to murine and rat CD36 was insensitive to changes in pH, and iodination significantly reduced binding. We further show that the differences observed in the binding phenotype of human and rodent CD36 can be attributed to a single residue. Site-directed mutagenesis of the histidine at position 242 of human CD36 to tyrosine (found in rodent CD36) conferred the binding phenotype of rodent CD36 onto human CD36. Furthermore, substitution of the tyrosine at position 242 of rat CD36 for histidine conferred the binding phenotype of human CD36 onto rat CD36. These findings suggest that residue 242 is part of, or important to the conformation of, the PE-binding domain of CD36.
Topics: Amino Acid Sequence; Animals; Binding Sites; CD36 Antigens; COS Cells; Cell Adhesion; Erythrocytes; Flow Cytometry; Histidine; Humans; Hydrogen-Ion Concentration; Mice; Molecular Sequence Data; Monoiodotyrosine; Mutagenesis, Site-Directed; Plasmodium falciparum; Rats; Structure-Activity Relationship; Tyrosine
PubMed: 9716613
DOI: No ID Found -
Protein Science : a Publication of the... Mar 2010Insect cells are useful for the high-yield production of recombinant proteins including chemokines and membrane proteins. In this study, we developed an insect...
Insect cells are useful for the high-yield production of recombinant proteins including chemokines and membrane proteins. In this study, we developed an insect cell-based system for incorporating non-natural amino acids into proteins at specific sites. Three types of promoter systems were constructed, and their efficiencies were compared for the expression of the prokaryotic amber suppressor tRNA(Tyr) in Drosophila melanogaster Schneider 2 cells. When paired with a variant of Escherichia coli tyrosyl-tRNA synthetase specific for 3-iodo-L-tyrosine, the suppressor tRNA transcribed from the U6 promoter most efficiently incorporated the amino acid into proteins in the cells. The transient and stable introductions of these prokaryotic molecules into the insect cells were then compared in terms of the yield of proteins containing non-natural amino acids, and the "transient" method generated a sevenfold higher yield. By this method, 4-azido-L-phenylalanine was incorporated into human interleukin-8 at a specific site. The yield of the azido-containing IL-8 was 1 microg/1 mL cell culture, and the recombinant protein was successfully labeled with a fluorescent probe by the Staudinger-Bertozzi reaction.
Topics: Amino Acids; Animals; Azides; Cell Line; Codon; Drosophila melanogaster; Escherichia coli; Genetic Code; Humans; Interleukin-8; Monoiodotyrosine; Phenylalanine; Promoter Regions, Genetic; Protein Biosynthesis; Tyrosine-tRNA Ligase
PubMed: 20052681
DOI: 10.1002/pro.322 -
The Journal of Biological Chemistry Dec 1990Clearance (C) receptors of atrial natriuretic factor (ANF) have an important role of removing ANF from the circulation. In the present study we investigated the cellular...
Clearance (C) receptors of atrial natriuretic factor (ANF) have an important role of removing ANF from the circulation. In the present study we investigated the cellular mechanisms of this function. 125I-ANF1-28 specifically bound to C-ANF receptors in cultured bovine vascular smooth muscle cells is internalized by a temperature-dependent process at a rate of 5% occupied receptors/min at 37 degrees C. Internalized 125I-ANF1-28 is rapidly metabolized and released to the medium as [125I]monoiodotyrosine, a process that is reversibly inhibited by NH4Cl (10 mM). Retroendocytosis of receptor-ligand complex is detectable when intracellular accumulation of the ligand is maximized by previous incubation with NH4Cl. In the presence of saturating concentrations of 125I-ANF1-28 when cells are warmed from 4 to 37 degrees C, there is first a decrease and then an almost complete replenishment of surface C-ANF receptors, a phenomenon that is not altered by protein synthesis inhibition with cycloheximide. In the absence of temperature transition, the density of surface C-ANF receptors remains constant, and by 2 h of incubation the amount of ANF hydrolyzed far exceeds the total amount of C-ANF receptors. The total population of surface C-ANF receptors is internalized and recycled every hour, and these processes are constitutive since they also occur in the absence of ligand. Trypsinization and solubilization experiments further indicate that C-ANF receptors are rapidly internalized and recycled to the cell membrane. The results demonstrate that receptor-ligand internalization, extensive receptor recycling, and lysosomal hydrolysis of ANF are the cellular mechanisms by which C-ANF receptors exert their clearance function.
Topics: Animals; Aorta; Atrial Natriuretic Factor; Cattle; Cells, Cultured; Endocytosis; Kinetics; Ligands; Muscle, Smooth, Vascular; Protein Binding; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface
PubMed: 2174430
DOI: No ID Found -
Biochemistry Jul 2015Reductive dehalogenation such as that catalyzed by iodotyrosine deiodinase (IYD) is highly unusual in aerobic organisms but necessary for iodide salvage from...
Reductive dehalogenation such as that catalyzed by iodotyrosine deiodinase (IYD) is highly unusual in aerobic organisms but necessary for iodide salvage from iodotyrosine generated during thyroxine biosynthesis. Equally unusual is the dependence of this process on flavin. Rapid kinetics have now been used to define the basic processes involved in IYD catalysis. Time-dependent quenching of flavin fluorescence was used to monitor halotyrosine association to IYD. The substrates chloro-, bromo-, and iodotyrosine bound with similar rate constants (kon) ranging from 1.3 × 10(6) to 1.9 × 10(6) M(-1) s(-1). Only the inert substrate analogue fluorotyrosine exhibited a significantly (5-fold) slower kon (0.3 × 10(6) M(-1) s(-1)). All data fit a standard two-state model and indicated that no intermediate complex accumulated during closure of the active site lid induced by substrate. Subsequent halide elimination does not appear to limit reactions of bromo- and iodotyrosine since both fully oxidized the reduced enzyme with nearly equivalent second-order rate constants (7.3 × 10(3) and 8.6 × 10(3) M(-1) s(-1), respectively) despite the differing strength of their carbon-halogen bonds. In contrast to these substrates, chlorotyrosine reacted with the reduced enzyme approximately 20-fold more slowly and revealed a spectral intermediate that formed at approximately the same rate as the bromo- and iodotyrosine reactions.
Topics: Biocatalysis; Catalytic Domain; Dinitrocresols; Humans; Iodide Peroxidase; Kinetics; Monoiodotyrosine; Oxidation-Reduction; Protein Binding; Thyroid Gland
PubMed: 26151430
DOI: 10.1021/acs.biochem.5b00410 -
The Biochemical Journal Oct 19691. The iodination of insulin was studied under various experimental conditions in aqueous media and in some organic solvents, by measuring separately the uptake of...
1. The iodination of insulin was studied under various experimental conditions in aqueous media and in some organic solvents, by measuring separately the uptake of iodine by the four tyrosyl groups and the relative amounts of monoiodotyrosine and di-iodotyrosine that are formed. In aqueous media from pH1 to pH9 the iodination occurs predominantly on the tyrosyl groups of the A chain. Some organic solvents increase the iodine uptake of the B-chain tyrosyl groups. Their efficacy in promoting iodination of Tyr-B-16 and Tyr-B-26 is in the order: ethylene glycol and propylene glycol approximately methanol and ethanol>dioxan>8m-urea. 2. It is suggested that each of the four tyrosyl groups in insulin has a different environment: Tyr-A-14 is fully exposed to the solvent; Tyr-A-19 is sterically influenced by the environmental structure, possibly by the vicinity of a disulphide interchain bond; Tyr-B-16 is embedded into a non-polar area whose stability is virtually independent of the molecular conformation; Tyr-B-26 is probably in a situation similar to Tyr-B-16 with the difference that its non-polar environment depends on the preservation of the native structure.
Topics: Chemical Phenomena; Chemistry; Dioxins; Electrolysis; Ethanol; Glycols; Hydrogen-Ion Concentration; Insulin; Iodine Isotopes; Methanol; Monoiodotyrosine; Sulfides; Tyrosine; Urea; Water
PubMed: 5346365
DOI: 10.1042/bj1150011 -
The Journal of Clinical Investigation Sep 1969The mechanism responsible for the hyperdynamic circulatory state in hyperthyroidism has not been defined. Although certain cardiac manifestations resemble those caused...
The mechanism responsible for the hyperdynamic circulatory state in hyperthyroidism has not been defined. Although certain cardiac manifestations resemble those caused by excessive adrenergic stimulation, recent evidence suggests that thyroid hormone exerts an effect on the heart that is independent of the adrenergic system. Since the inotropic and chronotropic effects of norepinephrine appear to be mediated by activation of adenyl cyclase, the possibility that thyroxine and triiodothyronine are also capable of activating adenyl cyclase was examined in the particulate fraction of cat heart homogenates.L-thyroxine and L-triiodothyronine increased the conversion of adenosine triphosphate-(32)P (ATP-(32)P) to cyclic 3',5'-adenosine monophosphate-(32)P (3',5'-AMP-(32)P) by 60 and 45% respectively (P < 0.01). A variety of compounds structurally related to the thyroid hormones, but devoid of thyromimetic activity did not activate adenyl cyclase: these included 3,5-diiodo-L-thyronine, L-thyronine, 3,5-diiodotyrosine, monoiodotyrosine, and tyrosine. D-thyroxine activated adenyl cyclase and half maximal activity was identical to that of the L-isomer. Although the beta adrenergic blocking agent propranolol abolished norepinephrine-induced activation of adenyl cyclase, it failed to alter activation caused by thyroxine. When maximal concentrations of L-thyroxine (5 x 10(-6) moles/liter) and norepinephrine (5 x 10(-5) moles/liter) were incubated together, an additive effect on cyclic 3',5'-AMP production resulted. THIS INVESTIGATION DEMONSTRATES: (a) thyroid hormone is capable of activating myocardial adenyl cyclase in vitro and (b) this effect is not mediated by the beta adrenergic receptor. Moreover, the additive effects of norepinephrine and thyroxine suggest that at least two separate adenyl cyclase systems are present in the heart, one responsive to norepinephrine, the other to thyroid hormone. These findings are compatible with the hypothesis that the cardiac manifestations of the hyperthyroid state may, in part, be caused by the direct activation of myocardial adenyl cyclase by thyroid hormone.
Topics: Adenine Nucleotides; Adenosine Triphosphate; Adenylyl Cyclases; Animals; Cats; Cyclic AMP; Enzymes; Heart; Heart Diseases; Hyperthyroidism; Myocardium; Norepinephrine; Phosphorus Isotopes; Propranolol; Thyroid Hormones; Thyroxine; Triiodothyronine
PubMed: 4309800
DOI: 10.1172/JCI106131