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)

Conditions favouring protein phosphorylation and dephosphorylation are examined for their effects on activity and charge heterogeneity of the rat gastric mucosal histidine decarboxylase. Incubation of gastric supernatant with various combinations of ATP, Mg2+, cyclic AMP and protein kinase under the blockade of endogenous phosphodiesterase and phosphatase fails to alter significantly enzyme activity as assayed with or without pyridoxal 5'-phosphate. Similar results are found with the purified enzyme. No change occurs in the distribution of activity between the charged forms. In contrast, treatment with alkaline phosphatase both inactivates the enzyme with preservation of heterogeneity, full reactivation being achieved by pyridoxal 5'-phosphate, and reduces the number of forms and converts forms II and III to form I with preservation of the catalytic potentialities. The data suggest that the enzyme heterogeneity may be related in part to the phosphorylation state; the possibility that the gastric enzyme is susceptible to several post-translational modifications is discussed.
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PMID:Relationship between the multiple forms of rat gastric histidine decarboxylase: effects of conditions favouring phosphorylation and dephosphorylation. 215 9

Osteoblastic cells were isolated from human maxilla by embedding the bone pieces in collagen gel. The isolated cells could be maintained in monolayer culture up to 50 population doubling levels (PDLs). Both parathyroid hormone (PTH) and prostaglandin E2 (PGE2) increased intracellular cyclic AMP level of the cells. The cells also showed high level of alkaline phosphatase (ALPase) activity and formed mineralized areas in monolayer culture. Electron microscopy demonstrated that these cells were surrounded by numerous well-banded collagen fibrils, among which matrix vesicles were scattered. It was also observed that needle-shaped crystals protruded from some matrix vesicles. These protruded crystals appeared to deposit along the collagen fibrils and a mineralized matrix was formed. The minerals of mineralized matrix mainly consisted of calcium and phosphorus and had the same Ca/P ratio as hydroxyapatite. These results indicate that the cells derived from human bone have characteristics of osteoblastic cells.
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PMID:In vitro mineralization of osteoblastic cells derived from human bone. 215 12

Brucellae are facultative intracellular bacterial pathogens that reside primarily in cells of the reticuloendothelial system. The high-speed supernatant obtained after centrifuging a suspension of Brucella abortus that had been frozen-thawed and sonicated contained abundant phosphomonoesterase activity, determined by using 4-methylumbelliferylphosphate as the substrate; this enzyme was purified 2,900-fold (yield, 570%) by chromatography on DE-52 cellulose and hydroxylapatite columns and high-performance liquid chromatography-gel filtration. The native enzyme had a molecular mass of 120,000 daltons (+/- 10,000 daltons), as determined by gel filtration chromatography, and resolved into two bands (60,000 and 66,000 daltons) when subjected to polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The B. abortus phosphomonoesterase had the following properties: pH optimum, 6.0 to 6.5; isoelectric point, 3.0; substrate specificity, 5'-AMP greater than 3'-AMP greater than 3'-GMP greater than 5'-GDP greater than 5'-CDP greater than 5'-CTP greater than 5'-UPT greater than phosphotyrosine greater than phosphoserine greater than phosphothreonine. The Km for 5'-AMP was 0.37 mM. Phosphatidylinositol 4,5-bisphosphate and myo-inositol 1,3,4-trisphosphate were poor substrates for the B. abortus enzyme. The phosphomonoesterase did not inhibit superoxide anion production by human neutrophils stimulated with formyl-methionyl-leucyl-phenylalanine. The phosphomonoesterase may be one of the bacterial enzymes in the pathway leading to the production of adenine, which is secreted by B. abortus and blocks the activation of neutrophils.
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PMID:Characterization of a phosphomonoesterase from Brucella abortus. 215 65

The influence of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on adenylate cyclase responsiveness in cultured osteoblastic cells was studied using a human osteosarcoma cell line SaOS-2. 1,25(OH)2D3 treatment had no effect on cell growth, cell protein and alkaline phosphatase activity. 1,25(OH)2D3 did not alter the basal production of cyclic AMP (cAMP) in intact cells, but the cAMP formation in response to parathyroid hormone (PTH), isoproterenol (ISO) and cholera toxin was attenuated by 1,25(OH)2D3. The response to forskolin, however, was unaffected by 1,25(OH)2D3 treatment. Islet activating protein failed to modify these 1,25(OH)2D3 effect. In cell free experiments, 1,25(OH)2D3 showed similar effect--that is, PTH and ISO-stimulated adenylate cyclase activity were attenuated, but forskolin-stimulated adenylate cyclase was unaffected. 1,25(OH)2D3 treatment had no effect on the kinetics of PTH binding to PTH receptor and on the ADP ribosylation of GTP stimulatory binding protein (Gs) in SaOS-2 cells. According to these results, 1,25(OH)2D3 appeared to change the coupling of Gs with adenylate cyclase, but does not affect receptor, Gs and adenylate cyclase themselves, nor GTP inhibitory binding protein.
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PMID:The effect of 1,25-dihydroxyvitamin D3 on human osteoblast-like osteosarcoma cell: modification of response to PTH. 216 Dec 22

X-ray microanalysis has been used to characterize the enzyme activity hydrolyzing the ATP analogue 5'-adenylylimidodiphosphate (AMP-PNP) in taste bud cells. Rabbit foliate papillae fixed with paraformaldehyde and glutaraldehyde were incubated cytochemically with AMP-PNP as the substrate and lead ion as capture agent. The reaction product which appeared on the microvilli of taste bud cells was examined using an energy dispersive X-ray microanalyzer connected to an analytical electron microscope. The X-ray spectrum thus obtained was compared with that obtained from the product obtained from the demonstration of ATPase activity. Comparison of the phosphorus/lead ratios in the two products showed that twice as much phosphorus was released from an AMP-PNP molecule by the activity in question compared with that released from an ATP molecule by ATPase activity. This indicates that the enzyme hydrolyzes AMP-PNP into AMP and imidodiphosphate and that the enzyme is adenylate cyclase or ATP pyrophosphohydrolase, which possesses a similar hydrolytic property, but not ATPase or alkaline phosphatase, which hydrolyzes AMP-PNP into ADP-NH2 and orthophosphate. This paper provides an example of the use of X-ray microanalysis as a tool for enzyme distinction. The method is applicable to a variety of enzymes and tissues.
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PMID:Identification of 5'-adenylylimidodiphosphate-hydrolyzing enzyme activity in rabbit taste bud cells using X-ray microanalysis. 216 24

The human hepatoma cell line (Li-7A) possesses a high concentration of epidermal growth factor (EGF) receptors and exhibits ectoATPase activity in the presence of either MgATP or CaATP (Knowles: J. Cell. Physiol., 134:109-116, 1988). Growth for 96 hours in the presence of both EGF and cholera toxin or another cyclic AMP elevating agent induced an ectoATPase activity which was more active with CaATP and resistant to inhibition by the sulfydryl reagent, p-chloromercuriphenylsulfonate (pCMPS) (Knowles: Arch. Biochem. Biophys., 263: 264-271, 1988). In contrast, treatment of cells with butyrate, a short chain organic acid which can be derived from the analogue, dibutyryl cyclic AMP, resulted in a 4-7-fold increase of an ectoATPase which was more active with MgATP and highly sensitive to pCMPS inhibition. Maximal induction by butyrate required 48 hours and was dependent on butyrate concentration, but was independent of EGF and cyclic AMP elevating agents. Of six organic acids tested, butyrate was most effective in the induction of the ectoMg2(+)-ATPase. The increase in the ectoMg2(+)-ATPase activity could be prevented with actinomycin D and cycloheximide, indicating that both transcription and translation were necessary for induction. In addition to the induction of the ectoMg2(+)-ATPase, butyrate induced alkaline phosphatase activity, but had no effect on a third ectoenzyme 5'-nucleotidase. These data further support our proposal that two distinct ectoATPases exist in the plasma membrane of Li-7A hepatoma cells.
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PMID:Butyrate induces an ectoMg2(+)-ATPase activity in Li-7A human hepatoma cells. 216 33

We investigated the differentiation-inducing effects of dibutyryl cyclic AMP (dBc AMP) on several cultured osteosarcoma cell lines (DUNN, MOLONEY, OST, FBJ). 1. Cell growth rates of all the osteosarcoma cell lines were reduced by 3mM dBc AMP. 2. Both alkaline phosphatase activity and 45Ca2(+)-uptake were promoted by 3mM dBc AMP. 3. There was, in each cell line except for the OST cells, a marked enlargement of the cell processes under the light microscopic observation. At the electron microscopic level, there were also many findings indicating an increase in cell functions. These results suggest that the differentiation may be induced by cAMP in osteosarcoma cells, and that the differentiation therapy by cAMP-related drugs is promising for a clinical application.
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PMID:[Experimental study on maturational therapy of osteosarcoma cell]. 216 18

We have examined the influence of parathyroid hormone (PTH) and 1,25(OH)2 vitamin D (1,25(OH)2D) on cytoskeletal assembly and biosynthesis in relation with cAMP production and parameters of cell growth and differentiation in normal human osteoblastic cells. Untreated human bone cells showed elongated morphology associated with high levels of actin, vimentin, alpha- and beta-tubulins and alpha-actinin as determined by 2-dimensional-gel electrophoresis and [35S]methionine labelling of cytoskeletal proteins. PTH (20 nM, 24 h) decreased the de novo biosynthesis of vimentin and alpha-actinin in human bone cells, an effect associated with a rise in intracellular cyclic AMP. In addition, PTH induced cytoskeletal disassembly as shown by a 52-70% decrease in the Triton-insoluble fractions of actin, alpha-tubulins and alpha-actinin. 1,25(OH)2D (10 nM, 24 h) also induced a 40-64% decrease in the polymerized fractions of actin, alpha-tubulins and alpha-actinin. These changes were associated with an 83% increase in osteocalcin production. Under these conditions, neither PTH nor 1,25(OH)2D at the doses tested affected alkaline phosphatase activity or cell growth as assessed by [3H]thymidine incorporation into DNA. The results show that PTH and 1,25(OH)2D induce similar inhibition of cytoskeletal proteins assembly involving microfilaments and microtubules in human osteoblastic cells. These alterations of cytoskeletal arrangement in response to PTH and 1,25(OH)2D may contribute to the functional response of human osteoblastic cells to these bone-resorbing hormones.
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PMID:Changes in cytoskeletal proteins in response to parathyroid hormone and 1,25-dihydroxyvitamin D in human osteoblastic cells. 216 75

The treatment of human platelets with the dibutyryl cyclic AMP (dbcAMP) revealed the presence of a 250 kDa protein which enhanced its GTP-binding activity. This protein was purified from platelet membranes by successive chromatographies on DEAE-cellulose, Ultrogel AcA34, Mono Q, HCA-hydroxyapatite, and TSK-3000SW columns. The positive cross-reaction of the 250 kDa protein with the anti-filamin antibody indicated that this protein is filamin or very close to it. The GTP gamma S-binding activity of this protein, when phosphorylated with cyclic AMP-dependent protein kinase (A-kinase), showed an over tenfold increase, with the specific activity being 3.6 nmol/mg protein. Dephosphorylation of the phosphorylated protein with alkaline phosphatase reduced the GTP gamma S-binding activity to the control untreated level.
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PMID:Enhancement of GTP gamma S-binding activity by cAMP-dependent phosphorylation of a filamin-like 250 kDa membrane protein in human platelets. 217 20

Bone cells derived from human trabecular explants display osteoblastic features. We examined the modulation of alkaline phosphatase activity and cAMP production as the result of exposing trabecular explants to physiologic concentrations of dexamethasone for 4 weeks during cellular outgrowth and subculture. Cells treated with dexamethasone were observed to grow generally more slowly than control cells. Cells appeared larger and more polygonal, and staining for alkaline phosphatase was more intense in the dexamethasone-exposed cultures. There was a progressive increase in cellular PTH responsiveness with increasing duration of exposure of cells to dexamethasone. Cells grown for 6 weeks in 3 x 10(-8) M dexamethasone had a 10-fold increase in PTH-stimulated cyclic AMP accumulation. Dexamethasone-treated cells also had a significantly increased alkaline phosphatase activity. 1,25-(OH)2D3-stimulated alkaline phosphatase activity was increased approximately 20-fold. cAMP responses were significantly increased to PTH (21.7-fold), PGE1 (2.67-fold), and forskolin (4.81-fold), but not to cholera toxin. Dexamethasone-treated cells also had a mean decrease in 1,25-(OH)2D3-stimulated osteocalcin production to 26.2% of control values (p less than 0.001). Hydrocortisone treatment gave rise to similar effects but of smaller magnitude than those of dexamethasone. Testosterone did not have a significant effect on alkaline phosphatase activity or cAMP production. Skin fibroblasts showed a significant enhancement of alkaline phosphatase activity in response to dexamethasone, but of a much smaller magnitude than in bone cells. The phenotypic changes induced by long-term culture in dexamethasone are consistent with the promotion of a more differentiated osteoblastic phenotype.
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PMID:Long-term effects of physiologic concentrations of dexamethasone on human bone-derived cells. 217 56


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