Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.3.1 (alkaline phosphatase)
47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Six rat liver plasma-membrane subfractions of different density and morphological, enzymic and chemical properties were prepared from homogenates by a combination of differential, rate-zonal and density-gradient centrifugation. They consisted of three vesicular 'light' subfractions of density 1.12-1.13 and three 'heavy' subfractions of density 1.16-1.18 containing membrane strips and intercellular junctions. 2. All six subfractions contained a basal adenylate cyclase activity. One of the 'light' subfractions that showed the highest glucagon-stimulated adenylate cyclase activity was identified as deriving form the blood-sinusoidal face of the hepatocyte. This subfraction, unlike the others, was contaminated by Golgi components, as indicated by its morphological properties and the presence of galactosyl- and sialyl-transferase activities. 3. All the six subfractions showed high activities of the following plasma-membrane marker enzymes: 5'-nucleotidase, alkaline phosphodiesterase (nucleotide pyrophosphatase), alkaline phosphatase, leucine naphthylamidase and Mg2+-activated adenosine triphosphatase. A 'light' subfraction that showed the highest specific activities of all the above marker enzymes, but lacked a glucagon-stimulated adenylate cyclase activity, was identified as deriving from the bile-canalicular face of the hepatocyte. 4. The 'heavy' subfractions, which showed generally the lowest activities of the above plasma-membrane enzyme markers, and were characterized by the presence of desmosomes and gap junctions, were taken to originate from the contiguous faces of the hepatocyte. 5. The protein composition of the six subfractions was generally similar, as shown by polyacrylamide-gel electrophoresis. Differences in the amounts of various protein and glycoprotein bands among the subfractions correlated with their morphology, enzymic composition and sialic acid content. 6. Hormonal and histochemical evidence supporting the identification of a bile-canalicular subfraction, a blood-sinusoidal subfraction and contiguous-face subfractions is discussed.
...
PMID:Functional polarity of the rat hepatocyte surface membrane. Isolation and characterization of plasma-membrane subfractions from the blood-sinusoidal, bile-Canalicular and contiguous surfaces of the hepatocyte. 12 84

A cytochemical method for the light and electron microscope localization of the K- and Mg-dependent phosphatase component of the Na-K-ATPase complex was applied to rat kidney cortex, utilizing p-nitrophenylphosphate (NPP) as substrate. Localization of K-N-ATPase activity in kidneys fixed by perfusion with 1% paraformaldehyde -0.25% glutaraldehyde demonstrated that distal tubules are the major cortical site for this sodium transport enzyme. Cortical collecting tubules were moderately reactive, whereas activity in proximal tubules was resolved only after short fixation times and long incubations. In all cases, K-NPPase activity was restricted to the cytoplasmic side of the basolateral plasma membranes, which are characterized in these neplron segments by elaborate folding of the cell surface. Although the rat K-NPPase appeared almost completely insensitive to ouabain with this cytochemical medium, parallel studies with the more glycoside-sensitive rabbit kidney indicated that K-NPPase activity in these nephron segments is sensitive to this inhibitor. In addition to K-NPPase, nonspecific alkaline phosphatase also hydrolyzed NPP. The latter could be differentiated cytochemically from the specific phosphatase, since alkaline phosphatase was K-independent, insensitive to ouabain, and specifically inhibited by cysteine. Unlike K-NPPPase, alkaline phosphatase was localized primarily to the extracellular side of the microvillar border of proximal tubules. A small amount of cysteine-sensitive activity was resolved along peritubular surfaces of proximal tubules. Distal tubules were unreactive. In comparative studies, Mg-ATPase activity was localized along the extracellular side of the luminal and basolateral surfaces of proximal and distal tubules and the basolateral membranes of collecting tubules.
...
PMID:Transport ATPase cytochemistry: ultrastructural localization of potassium-dependent and potassium-independent phosphatase activities in rat kidney cortex. 12 60

Methyl groups derived from 3H-methyl methionine were incorporated into vesicular stomatitis virus (VSV) MRNAs isolated from infected cells. Sequential degradation of the 12-18S viral mRNA species with ribonuclease T2, penicillium nuclease, and alkaline phosphatase yielded a single 3H-labeled dinucleotide. A similar resistant 32P-labeled fragment was obtained by digesting VSV mRNA uniformly labeled with 32P. This methylated and blocked oligomer was further cleaved with nucleotide pyrophosphatase, yielding two methylated 5' nucleotides. We postulate that the 5' terminal structure of the vivo 12-18S VSV mRNA contains 7-methylguanosine linked by a 5'-5' pyrophosphate bond to a methylated derivative of adenosine. In contrast to the mRNAs (+ strand), the VSV genome RNA ( MINUS STRAND) IS NOT BLOCKED.
...
PMID:Methylated and blocked 5' termini in vesicular stomatitis virus in vivo mRNAs. 16 1

Host cell and virus-specific poly(A)-containing RNAs isolated from nuclei and cytoplasm of monkey kidney cells infected with simian virus 40 contain different methylated nucleotides. In the cytoplasmic simian virus 40-specific RNA, about 75% of the radioactivity derived from (methyl-3-H)methionine was in N-6-methyladenosine (N-6mA) after digestion with Penicillium nuclease and bacterial alkaline phosphatase. The remainder was in a negatively charge component with properties of 5'-terminal structures, i.e., digestion with nucleotide pyrophosphatase and bacterial alkaline phosphatase released 2'-O-methyladenosine (A-m), 2'-O-methylguanosine (G-m), and 7-methylguanosine (m-7-G), consistent with a 5'-terminal structure of the type, m7-GpppNm. The nuclear virus-specific RNA contained N6mA, GM, 2'-O-methyluridine (U-m), and a smaller proportion (10%) of nuclease-, phosphatase-resistant presumptive 5' termini that also yielded A-m, G-m, and m7-G upon further hydrolysis. The infected cell nuclear and cytoplasmic RNAs that did not hybridize to DNA of simian virus 40 contained all four 2'-O-methylnucleosides. The possible role of methylation in the processing and translation of simian virus 40-specific mRNA is discussed.
...
PMID:Methylated simian virus 40-specific RNA from nuclei and cytoplasm of infected BSC-1 cells. 16 75

RNA extracted from CsC1-purified virions of tobacco mosaic virus is shown to give rise to an unusual nucleotide on digestion which RNAase T2, in addition to the four major nucleotides. This minor component has the electrophoretic characteristics of a phosphorylated end group, but is partially resistant to bacterial alkaline phosphatase. It is, however, a substrate for venom phosphodiesterase or nucleotide pyrophosphatase, yielding products which imply the structure m7G5'ppp5'Gp. TMV RNA, like many animal cellular and viral mRNAs recently examined, therefore has a 5' terminus blocked by a methylated nucleotide inverted with respect to the rest of the chain.
...
PMID:The 5' end group of tobacco mosaic virus RNA is m7G5' ppp5' Gp. 16 58

4-Nitrophenyl and 2-napthyl monoesters of phenylphosphonic acid have been synthesized, and an enzyme catalyzing their hydrolysis was resolved from alkaline phosphatase of a commerical calf intestinal alkaline phosphatase preparation by extensive ion-exchange chromatography, chromatography on L-phenylalanyl-Sepharose with a decreasing gradient of (NH4) 2SO4, and gel filtration. Detergent-solubilized enzyme from fresh bovine intestine was purified after (NH4)2SO4 fractionation by the same technique. The purified enzyme is homogeneous by polyacrylamide gel electrophoresis and sedimentation equilibrium centrifugation. It has a molecular weight of 108,000, contains approximately 21% carbohydrate, and has an amino acid composition considerably different from that reported from alkaline phosphatase from the same tissue. The homogeneous intestinal enzyme, an efficient catalyst of phosphonate ester hydoolysis but not of phosphate monoester hydrolysis, was identified as a 5'-nucleotide phosphodiesterase by its ability to hydrolyze 4-nitrophenyl esters of 5'-TMP but not of 3'-TMP. Also consistent with this identification was the ability of the enzyme to hydrolyze 5'-ATP to 5'-AMP and PPi, NAD+ to 5'-AMP and NMN, TpT to 5'-TMP and thymidine, pApApApA to 5'-AMP, and only the single-stranded portion of tRNA from the 3'-OH end. Snake venom 5'-nucleotide phosphodiesterase also hydrolyzes phosphonate esters, but 3'-nucleotide phosphodiesterase of spleen and cyclic 3',5'-AMP phosphodiesterase do not. Thus, types of phosphodiesterases can be conveniently distinguished by their ability to hydrolyze phosphonate esters. As substrates for 5'-nucleotide phosphodiesterases, phosphonate esters are preferable to the more conventional esters of nucleotides and bis(4-nitrophenyl) phosphate because of their superior stability and ease of synthesis. Furthermore, the rate of hydrolysis of phosphonate esters under saturating conditions is greater than that of the conventional substrates. At substrate concentrations of 1 mM the rates of hydrolysis of phosphonate esters and of nucleotide esters are comparable and both superior to that of bis(4-nitrophenyl) phosphate.
...
PMID:Hydrolysis of phosphonate esters catalyzed by 5'-nucleotide phosphodiesterase. 17 Sep 64

Plasma membranes from 6 spontaneously metastasizing and 4 non-metastasizing rat mammary carcinomata were isolated by discontinuous sucrose density gradient centrifugation of microsomal pellets. The starting microsomal fraction contained 40-50% plasma membranes as determined by the levels of 5'-nucleotidase activity, with a negligible amount of nuclear (1%), mitochondrial (5%) and lysomal (7%) contamination. Five distinct fractions (F1-F5) were banded at densities 1 X 09, 1 X 13, 1 X 15, 1 X 17 and 1 X 21 at 25 degrees C, in addition to a pellet (F6) obtained by centrifuging at 76,000 g for 17 h. The fractions F1 through F5, all contained various concentrations of membranous structures, while the pellet (F6) contained only amorphous materials as evidenced by electron microscopy. The F3 fraction at the gradient 1 X 15 had the highest specific as well as total activity of the plasma membrane marker enzyme, with aggregates of the least contaminated plasma membranes in vesicular forms. This fraction also had the lowest specific activity for glucose-6-phosphatase (smooth ER marker) and for beta-D-glucuronidase (lysomal marker), and therefore was considered to be the "cleanest" plasma membrane fraction. When the activity of 4 additional plasma membrane marker enzymes, i.e., alkaline phosphatase, phosphodiesterase I, nucleotide pyrophosphatase and alkaline ribonuclease was determined in the same F3 fraction, their levels were significantly lower in every metastasizing tumour than in the non-metastasizing ones, with the enzyme activity decreasing in direct proportion to the metastasizing capacity. On the other hand, the marker enzymes were high in all non-metastasizing tumours, with the activity seemingly increasing with the immunogenicity of tumour cells. There was no significant difference between the 2 groups of mammary tumours in the levels of sialic acid, hexosamine, phospholipid or cholesterol in the plasma membranes. Thus, the level of plasma membrane marker enzymes is considered an accurate indicator for metastasizing capacity in the rat mammary tumour system.
...
PMID:Plasma membrane associated enzymes of mammary tumours as the biochemical indicators of metastasizing capacity. Analyses of enriched plasma membrane preparations. 17 19

The nature of the stationary band of alkaline phosphatase, which occurs on starch gel electrophoresis of sera from patients with biliary obstruction, has been examined. Stationary alkaline phosphatase was eluted from Sepharose 4-B gel close to the void volume and together with the plasma membrane enzymes, nucleotide pyrophosphatase and 5'-nucleotidase, and with lipoprotein-X. Electron microscopy of concentrates of stationary alkaline phosphatase, prepared by ultracentrifugation and gel filtration, showed large (0.3--1 mum diameter) and small structures (30-70 nm diameter) by negative staining. The activity of the stationary alkaline phosphatase was associated in fixed sections with particles of about 10 nm X 40 nm resembling those of lipoprotein-X. It is suggested that the stationary alkaline phosphatase does not move into starch gel during electrophoresis because it is particulate. In agar electrophoresis the alkaline phosphatase which was stationary on starch gel moved towards the cathode with lipoprotein-X.
...
PMID:Serum alkaline phosphatase, nucleotide pyrophosphatase, 5'-nucleotide and lipoprotein-X in cholestasis. 17 32

Phosphodiesterase I from the venom of Bothrops atrox has been purified by successive chromatography on phosphocellulose P-11, hydroxyapatite, and DEAE-cellulose DE 52. The final product gave a single band on sodium dodecylsulfate-polyacrylamide gels and was free of endonuclease, 5' -nucleotidase, and unspecific alkaline phosphatase activity. It was concentrated in an Amicon ultrafiltrator without loss of activity and could be stored in 10 mM magnesium acetate and 10% glycerol at 4 degrees C for at least a year. Under optimal conditions, the enzyme reaction required 15 mM Mg2+ and a pH of 9.2. Phosphodiesterase I is relatively thermostable and, in the presence of a macromolecular substrate, was not denatured after 4 h at 55 degrees C. The pure enzyme offers new possibilities for sequence studies on highly structured nucleic acids at elevated temperatures.
...
PMID:Purification and characterization of phosphodiesterase I from Bothrops atrox. 17 76

Methylation patterns of Novikoff cytoplasmic mRNA were determined as a function of labeling time with L-[methyl-3H]methionine. The 5'-terminal m7G could be released from whole mRNA by treatment with nucleotide pyrophosphatase. Subsequent alkaline phosphatase treatment of this mRNA, followed by KOH digestion, yielded N'mpNp and N'mpNp from cap 1 (m7GpppN'mpN) and cap 2 (m7GpppN'mpN''mpN), respectively. Our results indicate that the relative amounts of labeled cap structures do change with time and that the amount of internal N6-methyladenosine decreases, relative to 5'-cap structures, as the cytoplasmic mRNAs age and the average size decreases. The formation of cap-2 structures by the addition of second 2'-O-methyl group at position N''m appears to be cytoplasmic event. Thus, after very short labeling times, greater than 80% of the labeled methyl groups in cap 2 are found in this position. These results, along with earlier data obtained on L-cell heterogeneous nuclear RNA methylation, are consistent with a model in which the nucleus is the cellular site of three mRNA methylation events producing 5'-terminal m7G, the first 2'-O-methylnucleoside (N'm) found in cap-1 structures and internal N6-methyladenosine. Subsequently, these nuclear methylations are followed by the cytoplasmic methylation at N''m. Analysis of the methynucleoside composition of cap-1 structures, along with comparable "core" structures (m7GpppN'm) generated from cap-2 by removal of N''m, indicates that at any single labeling time the methylnucleoside composition of a given cap-1 and the cap-2 "core" structure is remarkably similar. On the other hand, comparisons of the methylnucleoside composition of the cap structures at different labeling times indicate an increase in Cm in the first 2'-O-methylnucleoside (N'm) with time.
...
PMID:Kinetics of Novikoff cytoplasmic messenger RNA methylation. 18 13


1 2 3 4 5 6 7 8 9 10 Next >>

---