Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The subcellular localization of aminopeptidase N (previously called aminoendopeptidase) has been investigated. This enzyme was found to be partially released (30-40%) by osmotic shock or by converting Escherichia coli K10 cells to spheroplasts. However, in all other E. coli strains (K12, B/r, MRE 600, ML 308) tested, this enzyme is not released at all by these procedures and thus behaves like a cytoplasmic enzyme. The crypticity of aminopeptidase N is surprisingly low, 75-85% of the enzyme activity is directly assayable in intact cells of any E. coli strain. Various inhibitors of transport systems do not interfer with this assay. Aminopeptidase activity could also be assayed in spheroplasts, even when an insolubilized substrate was used, which suggests a surface location of this enzyme. As well, N-ethylmaleimide (0.4 mM), under conditions which do not allow penetration in the cytoplasm, caused 70% inhibition of aminopeptidase N. Binding of 125I-labeled antiaminopeptidase N antibody to spheroplasts (from K12 strain) was used to assay the orientation of aminopeptidase N in the membrane. This enzyme is exposed on the outer surface of the cytoplasmic membrane. Confirmation of this orientation was obtained by comparing the accessibility of aminopeptidase, alkaline phosphatase and beta-galactosidase to fluorescamine in intact cells. Only 16% of the total beta-galactosidase was labeled with this fluorescent reagent whereas 44-45% of the aminopeptidase N and 59% of the alkaline phosphatase were labeled. Electron microscopic visualization of insolubilized reaction products of aminopeptidase N within the cells showed that these products are located at the poles of the cells. Neither mutant cells which were devoid of aminopeptidase N activity nor parental strains with the enzyme activity inhibited with phenylmercuric chloride contained the characteristic black caps. Thus, it appears that the periplasm is enlarged at the poles of the cells and that the reaction product is mainly located in these places. Investigation of the type of interactions of aminopeptidase N with the plasma membrane only revealed that aminopeptidase N has mainly an electrostatic interaction with the outer surface, probably mediated by magnesium ion bridges. Additional interactions are involved since disruption of the integrity of the cytoplasmic membrane is required to totally release this enzyme.
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PMID:Aminopeptidase N from Escherichia coli. Unusual interactions with the cell surface. 32 10

Histochemical and immuno-histochemical studies on kidney sections of adult rats and rats at different stages of development were carried out to estimate enzyme concentrations in nephron segments. Aminopeptidase and alkaline phosphatase were found from 3 days before birth in proximal tubule cells, aldolase-B and aldolase-A in all the nephron and collecting duct. The concentration of the enzymes remained remarkably constant from the 3rd day after birth onwards, except for aldolase-A in the distal tubule cells. The concentration of aldolase-B was higher than of aldolase-A in the distal tubule cells. The concentration of aldolase-B was higher than of aldolase-A, in glomerula and proximal tubules, that of aldolase-A was higher than that of aldolase-B in the ascending thick part of the Henle loop and in the following parts of the nephron. This implies that the concentration of the enzymes is the limiting factor for the regulation of substrate hydrolysis and that the nephron when formed can function as efficiently as the nephron of the adult rat with respect to these enzymes.
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PMID:Aspects of regulation in kidney at the enzymic level: aldolase isozymes, aminopeptidase and alkaline phosphatase. 79 83

Logarithmic cultures of Saccharomyces cerevisiae strains LBG H 1022, FL-100, X 2180 1A and 1B were studied together with the mutants pep4-3, sec18-1 and sec7-1. The necessary ultrastructural observations showed that, as a rule, juvenile vacuoles were formed de novo from perinuclear endoplasmic reticulum cisternae (ER) packed and inflated with electron-dense (polyanionic) matrix material. This process was disturbed solely in the sec18-1 mutant under non-permissive conditions. The vacuolar marker enzymes adenosine triphosphatase (ATPase) and alkaline phosphohydrolase (ALPase) were assayed by the ultracytochemical cerium precipitation technique. The neutral ATPase was active in vacuolar membranes and in the previously shown (coated) microglobules nearby. ALPase activity was detected in microglobules inside juvenile vacuoles, inside nucleus and in the cytoplasm as well as in the membrane vesicles and in the periplasm. The sites of vacuolar protease carboxypeptidase Y (CPY) activity were assayed using N-CBZ-L-tyrosine-4-methoxy-2-naphthyl-amide (CBZ-Tyr-MNA) as substrate and sites of the amino-peptidase M activity using Leu-MNA as substrate. Hexazotized p-rosaniline served as a coupler for the primary reaction product of both the above proteases (MNA) and the resulting azo-dye was osmicated during postfixation. The CPY reaction product was found in both polar layers of vacuolar membranes (homologous to ER) and in ER membranes enclosing condensed lipoprotein bodies which were taken up by the vacuoles of late logarithmic yeast. Both before and after the uptake into the vacuoles the bodies contained the CPY reaction product in concentric layers or in cavities. Microglobules with CPY activity were also observed. Aminopeptidase was localized in microglobules inside the juvenile vacuoles. These findings combined with the previous cytochemical localizations of polyphosphates and X-prolyl-dipeptidyl (amino)peptidase in S. cerevisiae suggest the following cytologic mechanism for the biosynthetic protein transport: coated microglobules convey metabolites and enzymes either to the cell surface for secretion or enter the vacuoles in all phases of the cell cycle. The membrane vesicles represent an alternative secretory mechanism present in yeast cells only during budding. The homology of the ER with the vacuolar membranes and with the surface membranes of the lipoprotein condensates (bodies) indicates a cotranslational entry of the CPY into these membranes. The secondary transfer of a portion of CPY into vacuoles is probably mediated by the lipoprotein uptake process.
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PMID:Ultracytochemical localization of the vacuolar marker enzymes alkaline phosphatase, adenosine triphosphatase, carboxypeptidase Y and aminopeptidase reveal new concept of vacuole biogenesis in Saccharomyces cerevisiae. 253 Nov 29

Different enzymatic activities were studied in the human pancreatic cancer cell line CAPAN-1 in order to analyze their relation to differentiation. Alkaline phosphatase (Alk Ph), acid phosphatase, aminopeptidase, dipeptidyl peptidase IV, acid and neutral alpha-glucosidases, and acid beta-galactosidase were present. Especially alkaline phosphatase, which we have found to be of the placental type isoenzyme, is being highly expressed. Spontaneous cell differentiation at confluence as well as differentiating agents: sodium butyrate and DMSO, modulated the levels of three enzymes: Alk. Ph., aminopeptidase, and acid alpha-glucosidase. The exposure of the cells to the differentiating agents amplified the modulations occurring during the spontaneous differentiation. Aminopeptidase and acid alpha-glucosidase were found to be induced by differentiation. Alk Ph specific activity was significantly increased by the spontaneous and the butyrate-induced differentiations; whereas DMSO exerted an opposite effect, probably related to its biphasic action on cell proliferation.
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PMID:Modulation of enzymatic activities during spontaneous and induced differentiation in a human pancreatic adenocarcinoma cell line CAPAN-1. 254 14

We tested the hypothesis that the appearance of mucilage in the Northern Adriatic Sea was related with the accumulation of dissolved organic compounds released by intensive enzymatic activities and not utilized as direct substrate for microbial growth. To do this enzymatic activities and dissolved organic and inorganic pools in periods characterized by the presence of mucilage and in the same seasons but in absence of mucilage were compared. Extracellular enzymatic activities (aminopeptidase, beta-glucosidase and alkaline phosphatase), nutrient pool concentrations (total dissolved nitrogen, dissolved organic nitrogen, total dissolved phosphorus, dissolved organic phosphorus) and the biochemical composition of particulate and dissolved organic matter (in terms of proteins and carbohydrates) were determined on a monthly basis over a period of 3 years. Aminopeptidase and alkaline phosphatase activities displayed higher values in springs preceding the appearance of mucilage than in spring when no mucilage was observed. Beta-Glucosidase activity showed significantly higher values in summer periods characterized by the massive production of mucilage than in summers without mucilage events. The months preceding mucilage events were also characterized by an increase of the alkaline phosphatase to aminopeptidase activity ratio and by a significant accumulation of dissolved proteins. These findings, together with the significant increase of the DON/DOP ratio, suggest that mucilage formation is favoured by the deficiency of organic P. The present study provides compelling evidences that mucilage formation is favoured by the unbalance between organic matter mobilization by enzymatic activities and the accumulation of labile dissolved organic-N compounds.
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PMID:Exo-enzymatic activities and dissolved organic pools in relation with mucilage development in the Northern Adriatic Sea. 1622 8

Aminopeptidase-N (APN1) and alkaline phosphatase (ALP) proteins located in the midgut epithelium of Manduca sexta have been implicated as receptors for Cry1Aa, Cry1Ab, and Cry1Ac insecticidal proteins produced by Bacillus thuringiensis subsp. kurstaki. In this study, we analyzed the roles of ALP and APN1 in the toxicity of these three Cry1A proteins. Ligand blot analysis using brush border membrane vesicles of M. sexta showed that Cry1Aa and Cry1Ab bind preferentially to ALP during early instars while binding to APN was observed after the third instar of larval development. Cry1Ac binds to APN throughout all larval development, with no apparent binding to ALP. ALP was cloned from M. sexta midgut RNA and expressed in Escherichia coli. Surface plasmon resonance binding analysis showed that recombinant ALP binds to Cry1Ac with 16-fold lower affinity than to Cry1Aa or Cry1Ab. Downregulation of APN1 and ALP expression by RNA interference (RNAi) using specific double-stranded RNA correlated with a reduction of transcript and protein levels. Toxicity analysis of the three Cry1A proteins in ALP- or APN1-silenced larvae showed that Cry1Aa relies similarly on both receptor molecules for toxicity. In contrast, RNAi experiments showed that ALP is more important than APN for Cry1Ab toxicity, while Cry1Ac relied principally on APN1. These results indicated that ALP and APN1 have a differential role in the mode of action of Cry1A toxins, suggesting that B. thuringiensis subsp. kurstaki produces different Cry1A toxins that in conjunction target diverse midgut proteins to exert their insecticidal effect.
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PMID:Differential role of Manduca sexta aminopeptidase-N and alkaline phosphatase in the mode of action of Cry1Aa, Cry1Ab, and Cry1Ac toxins from Bacillus thuringiensis. 2368 67