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

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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 role of phosphatidylinositol-specific phospholipase C (PIase C) in a) the enigmatic phosphatidylinositol (PI) turnover and b) in our understanding of membrane enzyme-PI interactions is the subject matter of this article. PIase C is present in both procaryotes and eukaryotes. This enzyme is considered to be involved in the cells PI breakdown which occurs in response to several external stimuli. Recent information on the physical properties, Ca2+ requirement, cellular localization and modulation of the activity of PIase C of mammalian systems can help to evaluate the PI turnover from a new angle. Existing evidence suggests that Ca2+-dependent PI breakdown is probably mediated through the cytosolic and particulate PIase C while a Ca2+ independent pathway is catalyzed by a lysosomal enzyme. Apparently PI turnover may be operating through more than one mechanism. The association of this phenomenon with a membrane receptor event linked with "Ca2+ gating" may have to be reconsidered. Modulation of the PIase C activity by unsaturated amphiphiles or the presence of this enzyme in different physico-chemical forms could be a potential regulatory feature. Hydrolysis of membrane PI of a number of cells and tissues by the bacterial PIase C has been shown to cause substantial release of acetylcholinesterase, alkaline phosphatase and 5'-nucleotidase in free, soluble form. Other membrane enzymes, e.g., alkaline phosphodiesterase I, L-leucyl-beta naphthyl amidase and Ca2+ or Mg2+ ATPase are not affected. These results indicate a specific interaction between PI and certain enzymes in membranes. The chemical nature of this linkage, whether it is covalent or non-covalent, has also been explored and has provided intriguing insight into this phenomenon. New findings also indicate that hydrolysis of PI by PIase C also can cause modifications in membrane-enzyme activities, e.g., adenylate cyclase.
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PMID:Minireview. Phosphatidylinositol specific phospholipases C. 708 67

Preparations enriched with plasmalemmal, outer mitochondrial, or Golgi complex membranes from rat liver were subfractionated by isopycnic centrifugation, without or after treatment with digitonin, to establish the subcellular distribution of a variety of enzymes. The typical plasmalemmal enzymes 5'-nucleotidase, alkaline phosphodiesterase I, and alkaline phosphatase were markedly shifted by digitonin toward higher densities in all three preparations. Three glycosyltransferases, highly purified in the Golgi fraction, were moderately shifted by digitonin in both this Golgi complex preparation and the microsomal fraction. The outer mitochondrial membrane marker, monoamine oxidase, was not affected by digitonin in the outer mitochondrial membrane marker, monoamine oxidase, was not affected by digitonin in the out mitochondrial membrane preparation, in agreement wit its behavior in microsomes. With the exception of NADH cytochrome c reductase (which was concentrated in the outer mitochondrial membrane preparation), typical microsomal enzymes (glucose-6-phosphatase, esterase, and NADPH cytochrome c reductase) displayed low specific activities in the three preparations; except for part of the glucose-6-phosphatase activity in the plasma membrane preparation, their density distributions were insensitive to digitonin, as they were in microsomes. The influence of digitonin on equilibrium densities was correlated with its morphological effects. Digitonin induced pseudofenestrations in plasma membranes. In Golgi and outer mitochondrial membrane preparations, a few similarly altered membranes were detected in subfractions enriched with 5'-nucleotidase and alkaline phosphodiesterase I. The alterations of Golgi membranes were less obvious and seemingly restricted to some elements in the Golgi preparation. No morphological modification was detected in digitonin-treated outer mitochondrial membranes. These results indicate that each enzyme is associated with the same membrane entity in all membrane preparations and support the view that there is little overlap in the enzymatic equipment of the various types of cytomembranes.
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PMID:Analytical study of microsomes and isolated subcellular membranes from rat liver VIII. Subfractionation of preparations enriched with plasma membranes, outer mitochondrial membranes, or Golgi complex membranes. 725 62

The conjugated trihydroxy bile salts glycocholate and taurocholate removed approx. 20--30% of the plasma-membrane enzymes 5'-nucleotidase, alkaline phosphatase and alkaline phosphodiesterase I from isolated hepatocytes before the onset of lysis, as judged by release of the cytosolic enzyme lactate dehydrogenase. The conjugated dihydroxy bile salt glycodeoxycholate similarly removed 10--20% of the 5'-nucleotidase and alkaline phosphatase activities, but not alkaline phosphodiesterase activity; this bile salt caused lysis of hepatocytes at approx. 10-fold lower concentrations (1.5--2.0mM) than either glycocholate or taurocholate (12--16mM). At low concentrations (7 mM), glycocholate released these enzymes in a predominantly particulate form, whereas at higher concentrations (15 mM) glycocholate further released these components in a predominantly 'soluble' form. Inclusion of 1% (w/v) bovine serum albumin in the incubations had a small protective effect on the release of enzymes from hepatocytes by glycodeoxycholate, but not by glycocholate. These observations are discussed in relation to the possible role of bile salts in the origin of some biliary proteins.
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PMID:Effects of bile salts on the plasma membranes of isolated rat hepatocytes. 739 66

Prostasomes are human prostate derived organelles that were isolated from both prostatic fluid and seminal plasma for the present study. Specific activities were determined for prostasome membrane-associated enzymes, alkaline phosphatase (ALP), 5'-nucleotidase (5'NT), and alkaline phosphodiesterase I (APD). The mode of their membranous anchoring was studied by treatment of prostasomes with phosphoinositol-specific phospholipase C (PIPLC) and different detergents. A substantial amount of ALP (50%) and 5'NT (31%) was released by incubation of prostasomes with 2 U/ml of PIPLC contrary to the small amount of APD (12%) released by the same treatment. After PIPLC treatment, the enzymes were recovered in the aqueous phase after phase repartition in Triton X-114 indicating that PIPLC removed the hydrophobic domain converting the enzymes from membrane-linked to aqueous soluble forms. Octyl glycoside was the most efficient one among different detergents to solubilize the enzymes from the prostasome membrane. Both ALP and 5'NT were resistant to the treatment with Triton X-100 and Triton X-114. These results suggest that ALP, 5'NT, and APD are more or less extensively linked to the prostasome membrane via a glycophosphoinositide anchor.
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PMID:Association of some hydrolytic enzymes with the prostasome membrane and their differential responses to detergent and PIPLC treatment. 763 87

1. Ectoenzyme release from kidney brush border membranes of Rattus norvegicus and Sus scrofa domesticus by phosphatidylinositol-specific phospholipase C (PIPLC) of Bacillus thuringiensis was studied. 2. The levels of specific activities of ectoenzymes in R. norvegicus kidney brush border membranes were higher than those in S. scrofa domesticus. About 10-fold higher values were found for specific activities of alkaline phosphatase and gamma-glutamyl transpeptidase in R. norvegicus. 3. Alkaline phosphodiesterase I, alkaline phosphatase and 5'-nucleotidase were released from both R. norvegicus and S. scrofa domesticus brush border membranes, while gamma-glutamyl transpeptidase and dipeptidyl peptidase IV were not solubilized. The enzyme release by the action of PIPLC was suppressed when purified anti-PIPLC antibody was added to the reaction mixture. This suggests that enzyme release must be due to the direct action of PIPLC on kidney brush border membranes. 4. The released alkaline phosphodiesterase I from kidney of S. scrofa domesticus had a molecular weight of 240,000 and was activated by Mg2+ and Ca2+, but strongly inhibited by EDTA.
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PMID:Proof of alkaline phosphodiesterase I as a phosphatidylinositol-anchor enzyme. 839 52

This study investigated ectoenzyme release from small intestine brush border membranes (duodenum and jejunum, Preparation A; ileum, Preparation B) of mice by the action of phosphatidylinositol-specific phospholipase C or glycosyl-phosphatidylinositol-specific phospholipase D. Most of the alkaline phosphatase was solubilized from Preparation A, but about 60% was released from Preparation B. As for alkaline phosphodiesterase I activity, 15 and 10% were released from Preparations A and B, respectively. With Preparation B, octylglucoside treatment followed by phosphatidylinositol-specific phospholipase C or glycosyl-phosphatidylinositol-specific phospholipase D completely solubilized the alkaline phosphatase activity. However, this treatment did not change the ratio of release of alkaline phosphodiesterase I from Preparation A or B. These results indicate that the resistance to alkaline phosphatase found in Preparation B is due to hindered accessibility of the bonding splitting by phosphatidylinositol-specific phospholipase C and not to a modified glycosyl-phosphatidylinositolanchor.
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PMID:Release of ectoenzymes from small intestine brush border membranes of mice by phospholipases. 905 73

Phosphatidylinositol-specific phospholipase C (PI-PLC) from Bacillus thuringiensis added to a culture of LLC-PK1 cells inhibited cell growth by 40%. In contrast with normal cells, the cells cultured in the presence of PI-PLC showed needle-like appendages which seemed to have been formed due to portions of the cell remaining adhered to the culture dish as the cell shrank. When LLC-PK1 cells were treated with PI-PLC, significant amounts of alkaline phosphatase and alkaline phosphodiesterase I were released specifically from the apical surface of the LLC-PK1 cells. Furthermore, PI-PLC treatment caused a delay of enzyme production and dome formation. These data indicate that glycosyl-phosphatidylinositol (GPI)-anchored proteins on the surface of LLC-PK1 cells are important in cell growth and differentiation. Also, the combined use of LLC-PK1 cells and PI-PLC of B. thuringiensis is effective for investigating the function of GPI-anchor proteins.
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PMID:Growth inhibition, morphological change, and ectoenzyme release of LLC-PK1 cells by phosphatidylinositol-specific phospholipase C of Bacillus thuringiensis. 917 52

The amyloid precursor protein may be processed by several different pathways, one of which produces the amyloid beta-peptide betaA4 present in the amyloid plaques characteristic of Alzheimer's disease. A recent report suggested that axonal-amyloid precursor protein is present in a membrane fraction "with caveolae-like properties." In the present study we have isolated detergent-insoluble, caveolae-like membranes from both mouse cerebellum and the human neuroblastoma cell line SH-SY5Y. Detergent-insoluble membranes from mouse cerebellum retained nearly all of the glycosylphosphatidylinositol-anchored proteins--alkaline phosphatase, 5'-nucleotidase, and the F3 protein--while excluding the majority of the plasmalemmal marker protein alkaline phosphodiesterase I. Although the inositol trisphosphate receptor was highly enriched in this detergent-insoluble fraction, neither amyloid precursor protein nor clathrin immunoreactivity could be detected. Similar results were obtained with SH-SY5Y cells, where 5'-nucleotidase activity was enriched at least 30-fold in the detergent-insoluble membranes, but no amyloid precursor protein or clathrin immunoreactivity could be detected. Caveolin could not be detected in microsomal membranes from either mouse cerebellum or SH-SY5Y cells. These observations suggest that amyloid precursor protein is not normally present in detergent-insoluble, caveolae-like membrane microdomains.
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PMID:The amyloid precursor protein is not enriched in caveolae-like, detergent-insoluble membrane microdomains. 934 65

Three GPI-anchored proteins, aminopeptidase N, alkaline phosphatase and alkaline phosphodiesterase I were released from the midgut brush border membrane of Bombyx mori by phosphatidylinositol-specific phopholipase C and the aminopeptidase N was purified to a homogeneous state. N-terminus and 6 internal sequences, one of which possessed part of zinc-binding motif, showed homology with those from other species. The zinc content in purified aminopeptidase N was estimated as approximately 0.72 mol/mol of the protein and 1,10-phenanthroline completely inhibited the enzyme activity, suggesting zinc requirement for the activity. The aminopeptidase N activity was inhibited not only by probestin and actinonin, but also strongly depressed by amastatin, while leuhistin and bestatin were less inhibitory. These suggest that the active site of aminopeptidase N might be structurally different from those of mammals. Calcium and magnesium ions stimulated the aminopeptidase N activity, but copper ion was rather inhibitory. Zinc ion showed bi-modal effect on the activity, i.e., stimulatory at low concentration, but inhibitory at higher than 100 microM. This inhibition was completely restored by EDTA. These results suggest that the aminopeptidase N possesses two zinc ion-binding sites with high and low affinity as essential and inhibitory one, as well as some regulatory metal-binding sites.
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PMID:Characterization of aminopeptidase N from the brush border membrane of the larvae midgut of silkworm, Bombyx mori as a zinc enzyme. 960 61

Lipid rafts are regions of the plasma membrane that are enriched in cholesterol, glycosphingolipids and acylated proteins, and which have been proposed as sites for the proteolytic processing of the Alzheimer's amyloid precursor protein (APP). Lipid rafts can be isolated on the basis of their insolubility in Triton X-100 at 4 degrees C, with the resulting low-density, detergent-insoluble glycolipid-enriched fraction (DIG) being isolated by flotation through a sucrose density gradient. The detergent-insolubility of APP in mouse cerebral cortex relative to a variety of DIG marker proteins (alkaline phosphatase, flotillin, F3 protein and prion protein) and non-DIG proteins (alkaline phosphodiesterase I, aminopeptidase A and clathrin) has been examined. Alkaline phosphatase, flotillin, F3 protein and the prion protein were present exclusively in the DIG region of the sucrose gradient over a range of protein/detergent ratios used to solubilize the membranes and displayed a characteristic enrichment in the low-density fraction as the protein/detergent ratio was decreased. In contrast, most of the APP, alkaline phosphodiesterase I, aminopeptidase A and clathrin was effectively solubilized at all of the protein/detergent ratios examined. However, a minor proportion of these latter proteins was detected in DIGs at levels which remained constant irrespective of the protein/detergent ratio. When DIGs were isolated from the sucrose gradients and treated with excess Triton X-100, both the DIG marker proteins and APP, alkaline phosphodiesterase I and clathrin were predominantly resistant to detergent extraction at 37 degrees C. These results show that, although a minor proportion of APP is present in DIGs, where it is detergent-insoluble even at 37 degrees C, it behaves as an atypical lipid raft protein and raises questions as to whether lipid rafts are a site for its proteolytic processing.
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PMID:Amyloid precursor protein, although partially detergent-insoluble in mouse cerebral cortex, behaves as an atypical lipid raft protein. 1054 29


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