Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mammalian cytosolic thymidine kinase is one of a number of enzymes involved in DNA replication whose activities increase dramatically during S phase of the cell cycle. As a first step in defining the mechanisms that control the S phase induction of thymidine kinase activity, we have purified the human enzyme from HeLa cells and raised a specific immune serum against the purified protein. The enzyme was isolated from cells arrested in S phase by treatment with methotrexate and purified to near homogeneity by ion-exchange and affinity chromatography. Stabilization of the purified enzyme was achieved by the addition of digitonin. An electrophoretic Rm of 0.2 in nondenaturing gels characterizes the purified enzyme activity as cytosolic thymidine kinase. The enzyme has a Stoke's radius of 40 A determined by gel filtration and a sedimentation coefficient of 5.5 S determined by glycerol gradient sedimentation. Based on these hydrodynamic values, a native molecular weight of 96,000 was calculated for the purified enzyme. When electrophoresed in denaturing sodium dodecyl sulfate-polyacrylamide gels under reducing conditions, the most purified enzyme fraction was found to contain one predominant polypeptide of Mr = 24,000. Several lines of evidence indicate that this polypeptide is responsible for thymidine kinase enzymatic activity. 1) The Mr = 24,000 polypeptide co-migrates with thymidine kinase activity in electrophoretic and sedimentation analyses. 2) A subunit Mr = 25,504 is predicted by the nucleotide sequence of a recently isolated cDNA clone that encodes HeLa thymidine kinase. 3) Mouse LTK- cells transformed with this clone express a cytosolic thymidine kinase activity, as well as a novel Mr = 24,000 polypeptide detectable with immune serum raised against the purified human enzyme.
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PMID:Human cytosolic thymidine kinase. Purification and physical characterization of the enzyme from HeLa cells. 333 3

We examined the role of the pressure natriuresis phenomenon in long-term arterial pressure control. Uninephrectomized dogs were housed in metabolic cages and made hypertensive with a continuous background intravenous infusion of angiotensin II (AngII, 12 ng/kg/min). To increase the ability of the kidney to excrete salt and water, we infused acetylcholine (ACH, 2.0 micrograms/kg/min), a potent natriuretic agen, directly into the renal artery. In four dogs, ACH decreased mean arterial pressure (MAP) from 144 +/- 5 mm Hg to 113 +/- 3 mm Hg. Sodium excretion increased by about 60% on the first day of infusion and then returned rapidly toward the control value. On cessation of the ACH infusion, there was a transient but marked sodium retention, and the hypertension returned. A control infusion of ACH intravenously rather than into the renal artery in the same four dogs did not affect MAP or sodium excretion during AngII hypertension.
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PMID:Hypotensive effect of chronic intrarenal infusion of acetylcholine during angiotensin hypertension. 337 Jan 36

To elucidate the change in EPH gestosis placental amino acid transport activity, we investigated the uptake of L-alanine into microvillous membrane vesicles prepared from EPH gestosis placenta and from normal placenta by using a rapid filtration technique. 1. Alkaline phosphatase (ALP) was the marker enzyme of microvillous membrane vesicles (MMV). The ALP activity of mild EPH gestosis placental MMV didn't differ from that of normal placental MMV. On the other hand, the ALP activity of severe EPH gestosis placental MMV decreased compared to that of normal placental MMV. 2. The uptake of L-alanine into human placental MMV was dependent on the Na+ electrochemical gradient, so the transport across human placental MMV was a secondarily active one. The L-alanine transport activity of mild EPH gestosis placental MMV didn't differ from that of normal placental MMV. On the other hand, the L-alanine transport activity of severe EPH gestosis placental MMV decreased prominently compared to that of normal placental MMV.
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PMID:[The changes in EPH gestosis placental amino acid transport activity (using human placental microvillous membrane vesicles)]. 342 74

Somatic cell mutants with altered K+ transport have previously been isolated from mutagenzied LMTK- cells for their ability to grow at subthreshold low-potassium concentrations (0.2 mM). These mutants fall into two classes: one class, LTK-5, possesses a functionally altered furosemide-sensitive Na+-K+-Cl- cotransport system and the other, LTK-1, an altered K+-conducting channel. Somatic cell hybrids have been formed between each of these cell lines and a wild-type L-cell line, making use of complementing selectable marker mutations carried by these parents, to establish the dominance of the K+ transport mutations. Hybrids were isolated and studied in two ways: clonal hybrid cell lines were selected in a manner unbiased toward their K+ transport phenotype, which was later assayed; and the number of independent hybrids arising in this single-selective condition was compared with the number arising in a condition which is double selective for the mutant phenotype as well. By both assays, hybrids formed with LTK-1 or LTK-5 as a parent uniformly exhibited the mutant phenotype by growth and cloning, whereas control hybrids with LMTK- as parent never did. This demonstrates both transport mutations to be dominant and thus potentially isolatable.
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PMID:Selectable mutations altering two mechanisms of mammalian K+ transport are dominant. 357 4

We investigated the biosynthesis of the human insulin receptor in IM-9 lymphocytes and HEP-G2 hepatoma cells. Cells were first pulse labeled for 15 min with [35S]methionine and then chased for up to 4 h. At each time, the cells were solubilized in 1% Triton X-100; the insulin receptor was immunoprecipitated and then analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (6%) and fluorography. At 15 min, a major precursor protein of 190,000 Mr was precipitated. During the chase period, two smaller proteins became apparent, which evolved into two major species of 130,000 and 95,000 Mr, the mature alpha- and beta-subunits, respectively. When IM-9 cells were trypsinized after pulse chase, the alpha- and beta-subunits were completely digested, whereas the 190,000-Mr precursor was unaffected. 125I-surface labeling of cells, followed by immunoprecipitation, revealed the presence of only the alpha- and beta-subunits, indicating that only these two species were on the cell surface. To study this biosynthetic pathway, several inhibitors were used (tunicamycin, monensin, and swainsonine). These inhibitors revealed the following. The receptor is first synthesized as a 170,000-Mr protein that is cotranslationally N-glycosylated to yield a high-mannose 190,000-Mr precursor. This precursor is rapidly transported from the endoplasmic reticulum to the Golgi apparatus where it is cleaved into two subunits of 120,000 Mr (alpha) and 90,000 Mr (beta). These subunits then increase in molecular weight by processing of the high-mannose oligosaccharides to the low-mannose complex type. The two subunits then migrate to the cell surface where they function to transmit the insulin signal.
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PMID:Biosynthesis and processing of the human insulin receptor. 372 Oct 67

Cultured A6 epithelial cells from toad kidney form confluent monolayers with tight junctions separating the apical and basolateral membranes. These two membrane domains have distinct compositions and functions. Thus, sodium is actively transported across the epithelia from the apical to basolateral surface via amiloride-inhibitable sodium channels located in the apical membrane. Sodium transport is stimulated by vasopressin, cholera toxin, and 8-bromo-cAMP applied to the basolateral surface where the receptors, adenylate cyclase, and Na+/K+-ATPase are located. In a previous study (Spiegel, S., Blumenthal, R., Fishman, P.H., and Handler, J.S. (1985) Biochim. Biophys. Acta 821, 310-318), we demonstrated that exogenous gangliosides inserted into the apical membrane of A6 epithelia do not redistribute to the basolateral membrane. With the ability to vary selectively the ganglioside composition of the apical membrane, we examined the effects of gangliosides on sodium transport in A6 epithelia. When the apical surface of A6 epithelia were exposed to exogenous gangliosides, sodium transport in response to vasopressin, cholera toxin, and 8-bromo-cAMP was enhanced compared to epithelia not exposed to gangliosides. The effect was observed with bovine brain gangliosides, NeuAc alpha 2----3Gal beta 1----3GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4Glc beta 1----Cer (GD1a) and Gal beta-1----3GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4Glc beta 1----Cer (GM1), but not with the less complex ganglioside, Neu-Ac alpha 2----3Gal beta 1----4Glc beta 1----Cer (GM3). We examined A6 cells for endogenous gangliosides and found that, whereas GM3 was a major ganglioside, only trace amounts of GM1 and GD1a were present. Based on cell surface and metabolic labeling studies, these gangliosides were synthesized by the cells and were present on the apical as well as the basolateral surface. Bacterial sialidase, which hydrolyzes more complex gangliosides to GM1, was used to modify the endogenous gangliosides on the apical surface; after sialidase treatment, the epithelia were more responsive to vasopressin, cholera toxin, and 8-bromo-cAMP. Thus, gangliosides may be modulators of sodium channels present in the apical membrane of epithelial cells.
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PMID:Gangliosides modulate sodium transport in cultured toad kidney epithelia. 378 88

A porcine brain dipeptidyl-aminopeptidase (DAP) has been purified more than 2400-fold from a crude mitochondrial fraction containing synaptosomes. This enzyme catalyzes the release of free Tyr-Gly from Leu-enkephalin (Km = 2.5 microM) with an optimal activity between pH 6.0 and pH 8.0. The enzyme appears homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis devoid of detectable contaminating aminopeptidase activities. The native enzyme is a monomeric protein with a molecular weight of 51,000 +/- 1,000 and an isoelectric point of 4.6 +/- 0.1. This enzyme cosediments with synaptosomes on a Ficoll-sucrose gradient and is partially associated with synaptic plasma membranes. Its activity is inhibited by the metal-chelating agents ethylenediaminetetraacetate and o-phenanthroline. It is not inhibited by the OH-reactive agent phenylmethanesulfonyl fluoride and SH-reactive agents such as p-(chloromercuri)benzoate and N-ethylmaleimide. Among the various biologically active peptides tested, the purified enzyme releases efficiently the N-terminal dipeptide moiety from enkephalins, Trp-Met-Asp-Phe-NH2 (CCK4), and Gly-Trp-Met-Asp-Phe-NH2 (CCK5). At variance, the native peptides CCK8, substance P, neurotensin, and angiotensin II are not cleaved by the DAP. This enzyme is different from other unspecific DAPs, as well as from enkephalin-degrading DAPs previously reported, by its molecular weight and substrate specificity.
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PMID:Purification and characterization of an enkephalin-degrading dipeptidyl-aminopeptidase from porcine brain. 381 77

Sodium dl-4-[1R,2R,3aS,8bS)-1,2,3a,8b-tetrahydro- 2-hydroxy-1-[(3S,4RS)-3-hydroxy-4-methyl-oct-6- yne-(E)-1-enyl]-5-cyclopenta[b]benzofuranyl]butyrate (TRK-100) is a stable analogue of prostacyclin (epoprostenol, PGI2). The drug was shown to be a potent inhibitor of platelet aggregation in vitro, induced by adenosine diphosphate (ADP), using platelet-rich plasma (PRP) from human and several animal species. The inhibitory activity of TRK-100 using human platelets was half that of PGI2 and eight times that of PGE1. There was a marked tendency for platelet clumps to disaggregate following secondary aggregation in the presence of TRK-100 at final concentrations higher than 1 ng/ml. This activity was similar to PGI2 and more than 30 times that of PGE1. TRK-100 was shown to induce the disaggregation of a pre-existing thrombus in the microcirculation of the hamster cheek pouch. A dose-dependent response was obtained following oral administration of the drug at levels of 50-200 micrograms/kg. Optimal activity was observed 30-60 min after dosing and activity was sustained throughout the experimental period. TRK-100 was more active than PGE1 in the test system and appeared to be of a similar potency to PGI2. Since this drug is stable, orally active and without the hypotensive activity of PGI2, it is considered to be a potentially useful agent for antithrombotic therapy.
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PMID:Effect of a stable prostacyclin analogue on platelet function and experimentally-induced thrombosis in the microcirculation. 391 23

The ultrastructural response of the uterine luminal epithelium of the spayed virgin rat was studied as a parameter in screening the effects of antifertility agents which may interfere with implantation. The agents studied were bis-(p-acetoxyphenyl-2-methyl-cyclohexlidene-methane (F-6103), bis-(p-acetoxyphenyl)-2-methyl-4-methylidene-cyclohexylidene-methane (F- 6255), bis-(p-acetoxyphenyl)-1,2,3,4-tetrahydro-1-naphtylidene-methane ( F-6278), trans-(p-2-dimethylaminoethoxyphenyl) -1,2-diphenyl-1-ene (ICI- 46474), 1-(p-(2-diethylaminoethoxy) phenyl) -2-(p-methoxyphenyl-1-phenylethane (MER-25), 3-ethyl-2-methyl-4-pheny; -4-cyclohexenecarboxylic acid, sodium salt (ORF-4563), 1-(2-(p-(3,4,-dihydro-6-methoxy-2-phenyl-1-naphtyl)-phenoxy) ethyl)pyrro lidine, HCI(U-11100A), 2(p-(6-methoxy-2-phenylinden-3-yl) phenoxy)trieth ylamine, HCI (U-11555A) and 2-phenyl-1-p-(beta-pyrrolidinoethoxy) phenyl naphto(2,1-b)-furan (66/179). The substances were tested in spayed rats in spayed rats given progesterone and in spayed rats given progesterone plus estradiol-17 beta. All agents gave an estrogen-like response when given separatly. The response was most marked with the F-compounds and ORF-4563. The F-compounds and ORF-4563 changed the ultrastructure profoundly in progesterone-treated rats while the other compounds had little effect. Progesterone plus estradiol rendered the epithelium suitable for implantation. Each compound except U-1155A inhibited the attachment reaction when given before estradiol.
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PMID:Attachment reaction of rat uterine luminal epithelium. V. Suppression of the attachment reaction by some antifertility agents. 465 Jun 61

Postoperative pulmonary embolism continues to be a problem in patient care, especially in high-risk patients. This study was designed to evaluate a combined pharmacologic approach to the prophylaxis of postoperative deep venous thrombosis (DVT) by mediating at least two and probably three of Virchow's predisposing factors. Patients 40 years of age and older undergoing operations greater than 45 minutes under general anesthesia were placed in one of five treatment groups and studied by a prospective randomized, double-blind protocol. Study drugs were the following: (1) 0.5 mg of dihydroergotamine plus 5000 IU of sodium heparin (DHE 5000), (2) 0.5 mg DHE plus 2500 IU heparin (DHE 2500), (3) 5000 IU of HEP (HEP 5000), (4) 0.5 mg of DHE (DHE 0.5), and (5) a placebo. Study medications were administered 2 hours preoperatively and continuously thereafter every 12 hours postoperatively subcutaneously in the anterior abdominal wall for 5 to 7 days or until a positive radiofibrinogen uptake test (RFUT). The RFUT was performed according to standardized technique and was used to establish the presence or absence of DVT. This report is an analysis of the major subgroup of patients undergoing intra-abdominal operations. Results showed a highly statistically significant prophylactic benefit from DHE 5000 compared with the placebo (p less than 0.003) and all other treatment groups (p less than 0.05). There was no significant benefit from DHE 2500, HEP 5000 (p greater than 0.13), and DHE 0.5 (p greater than 0.3). All patients who entered the study had two or more risk factors for postoperative DVT, and high-risk patients were distributed equally throughout all treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prophylactic efficacy of low-dose dihydroergotamine and heparin in postoperative deep venous thrombosis following intra-abdominal operations. 638 9


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