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R Taguchi

Publications and source records attributed to R Taguchi.

At least 55 records · Page 3Linked to original sources
PubMed1990

Analysis of PI (phosphatidylinositol)-anchoring antigens in a patient of paroxysmal nocturnal hemoglobinuria (PNH) reveals deficiency of 1F5 antigen (CD59), a new complement-regulatory factor.

FACS analysis together with PIPLC treatment was applied to PI-anchoring antigens such as DAF (decay-accerelating factor, CD55), 1F5 antigen (CD59), CD14 and CD16 on the cell surfaces of blood cells from a normal adult and a male patient with paroxysmal nocturnal hemoglubinuria (PNH). Through the extensive analysis, this patient proved to be completely defective in 1F5 antigen, a newly found complement-regulatory protein, on all the blood cells tested. In normal blood cells such as lymphocytes, monocytes and granulocytes, 1F5 antigen was expressed as one of PI-anchoring proteins. In contrast to most of PNH patients, this patient reserved DAF, CD14 and CD16 at normal levels in his erythrocytes, monocytes and granulocytes. Also, there were no significant differences between the normal adult and the patient in the activities of erythrocyte acetylcholinesterase and granulocyte alkaline phosphatase which were also known to be PI-anchoring enzymes. Thus, deficiency of 1F5 antigen must be deeply related to the clinical symptoms of PNH in this patient.

Adult↗
PubMed1990

Secondary structure of sphingomyelinase from Bacillus cereus.

Of the total of 306 amino acids in the sequence of sphingomyelinase (SMPLC) from Bacillus cereus, almost half (150) are expected to be involved in the formation of loop or turn structure, while 65 and 73 residues may participate in the formation of alpha-helix and beta-structure, respectively. The helix content of SMPLC was calculated to be 0-5%, based on the CD spectra. The addition of divalent metal ions such as Mg2+ or both Ca2+ and Mg2+ had no effect on the CD spectra of SMPLC, although the addition of these metal ions caused the breakdown of membranous SM and specific adsorption of SMPLC onto erythrocyte membranes. A hydropathy study showed that SMPLC has hydrophobic regions at the N-terminal domain which must be responsible for the binding of the enzyme to the membranes. The partial homologies between the amino acid sequences of SMPLC and Clostridium perfringens alpha-toxin (phospholipase C) are discussed.

Amino Acid Sequence↗
PubMed1990

Determination of the molecular nature and cellular localization of Thy-1 in human renal tissue.

The molecular nature and cellular localization of Thy-1 antigen in human renal tissue were studied. Strong immunohistochemical staining was observed in frozen sections of human kidney using monoclonal anti-human Thy-1 antibody; this reaction was almost completely abolished by pretreating the kidney section with phosphatidyl inositol (PI)-specific phospholipase C (PI-PLC). Immunohistochemical analysis revealed that the Thy-1 antigen is localized on the proximal tubular epithelial cells and the Bowman's capsule of the glomerulus. Northern blot analysis of renal mRNA using a cloned human Thy-1 gene revealed the presence of human Thy-1 mRNA of a similar size to the one in human brain. When a human kidney cDNA library was screened with the same probe, a cDNA of human Thy-1 was isolated. Moreover, human Thy-1 protein with a molecular weight (MW) of 21,000 was detected in renal tissue by gel electrophoresis and Western blot analysis using monoclonal anti-human Thy-1 antibody. These data demonstrate for the first time the production of human Thy-1 as a PI-anchored protein with a unique cellular location in human renal tissue.

Adult↗
PubMed1989

Complete deficiency of 20 KDa homologous restriction factor (HRF20) and restoration with purified HRF20.

20 KDa homologous restriction factor (HRF20) is a membrane glycoprotein which inhibits formation of membrane attack complexes of homologous complement. Erythrocytes from a patient who is completely deficient in HRF20 were readily hemolyzed by homologous complement activated by sucrose or by acidification as in paroxysmal nocturnal hemoglobinuria (PNH). After incubating PNH erythrocytes (PNH-E) with purified HRF20, the cells were analyzed by flow cytometry using a monoclonal antibody to HRF20 and shown to have the antigen absorbed. These PNH-E acquired resistance to hemolysis by homologous complement suggesting that HRF20 may be successfully used for treatment of these patients.

Adult↗
PubMed1989

Release of PI-anchoring enzymes and other effects of phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis on TN-368 cells from a moth ovary.

Release of PI-anchoring enzymes and other effects of phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis on TN-368 cells from a moth ovary. Toxicon 27, 637-645, 1989.--The effect of phosphatidylinositol-specific phospholipase C(PIPLC) from Bacillus thuringiensis was investigated on TN-368 cells, derived from the ovary of a moth, Trichoplusia ni. Quantitative analysis of lipids showed that phosphatidylinositol (PI) was contained as one of the major phospholipids in TN-368 cells, whereas sphingomyelin and cholesterol were minor lipid components. When TN-368 cells were treated with PIPLC, significant amounts of alkaline phosphatase, 5'-nucleotidase and beta-glucosidase were released from these cells. Thus, these enzymes were shown to be PI-anchoring proteins in the plasma membrane of these cells. In the presence of 4.2 units of PIPLC, the cell growth of TN-368 was inhibited by 50%. In contrast with normal cells, the cells cultured in the presence of PIPLC became swollen and globular, losing their protoplasmic extensions. Also, there was degeneration of the interior of TN-368 cells cultivated in the presence of PIPLC. Mitochondria became swollen with a decrease in number of granules while the crista turned transparent. Also, an increase in lysosomes was observed and vacuoles seemingly derived from smooth endoplasmic reticula appeared.

Animals↗
PubMed1989

Membrane anchors of alkaline phosphatase and trehalase associated with the plasma membrane of larval midgut epithelial cells of the silkworm, Bombyx mori.

The larval midgut epithelial cell of the silkworm, Bombyx mori, has two forms of alkaline phosphatase and trehalase, soluble and membrane-bound. Alkaline phosphatase and trehalase of the latter form are found in the brush border membrane and the basolateral membrane, respectively. In this work we studied the membrane anchors of these membrane-bound enzymes. Alkaline phosphatase was solubilized by phosphatidyl-inositol-specific phospholipase C, but not by papain. Conversely, trehalase was released from the membrane by papain, but not by phosphatidylinositol-specific phospholipase C. Both enzymes were solubilized in an amphiphilic form with 0.5% Triton X-100 plus 0.5% sodium deoxycholate (pH 7.0). The detergent-solubilized alkaline phosphatase and trehalase were converted to hydrophilic form on incubation with phosphatidylinositol-specific phospholipase C and papain, respectively. The effects of papain on solubilization and conversion of trehalase were completely inhibited by leupeptin. These results suggest that, in the silkworm larvae, alkaline phosphatase is anchored in the brush-border membrane via a glycosyl-phosphatidylinositol, while trehalase is associated with the basolateral membrane through a hydrophobic segment of the polypeptide.

Alkaline Phosphatase↗
PubMed1989

5'-Nucleotidase in rat liver lysosomal membranes is anchored via glycosyl-phosphatidylinositol.

We have previously demonstrated that 5'-nucleotidase, known as a plasma membrane enzyme, is also distributed both in rat liver tritosomal membranes and contents (J. Biochem. 101, 1077-1085, 1987). When the lysosomal membranes isolated from rat livers were incubated with phosphatidylinositol-specific phospholipase C purified from B. thuringiensis, about 70% of 5'-nucleotidase activity was released from the membranes. Judging from the result by phase separation with Triton X-114, the enzyme solubilized by the phospholipase C digestion showed a hydrophilic nature such as that of the tritosomal contents. Immunoblot analysis showed that the molecular weight of 5'-nucleotidase released from the lysosomal membranes by the phospholipase C digestion was almost identical with that of the enzymes from the Tritosomal contents. The above results showed that the phosphatidylinositol-specific phospholipase C-like enzyme in the lysosomes may be responsible for the conversion of the lysosomal membrane-bound 5'-nucleotidase to the soluble form present in the lysosomal matrix.

5'-Nucleotidase↗
PubMed1989

Rat mesangial cells actively produce phosphatidylinositol-anchored Thy-1.

We provide evidence that the mesangial cells of rat kidney glomeruli express Thy-1 as a phosphatidylinositol-anchored protein. Both the mesangial area of kidney, examined in tissue sections, and mesangial cells maintained in culture for more than 3 months, showed prominent immunofluorescence staining with an anti-Thy-1 monoclonal antibody (OX7); this staining was almost completely abolished by pretreating kidney sections or mesangial cells with the phosphatidylinositol-specific enzyme, phospholipase C. By Northern blotting, mesangial cells were shown to express mRNA of an appropriate size, hybridizing to a mouse Thy-1.1-specific probe.

Animals↗
PubMed1987

Determination of covalently bound myo-inositol in bovine erythrocyte acetylcholinesterase and porcine kidney alkaline phosphatase.

Bovine erythrocyte acetylcholinesterase and porcine kidney alkaline phosphatase were purified to a homogeneous state. By using gas chromatography-mass spectrometry, we demonstrated the presence of covalently bound myo-inositol in these purified enzymes. The quantitative data suggest that one molecule of myo-inositol is bound to each subunit of these enzyme proteins. The covalently bound inositol was removed from these enzyme molecules by deamination with nitrous acid, suggesting the possibility that myo-inositol is directly bound to amino sugar.

Acetylcholinesterase↗
PubMed1987

The action of sphingomyelinase from Bacillus cereus on ATP-depleted bovine erythrocyte membranes and different lipid composition of liposomes.

The presence of cholesterol or phosphatidylethanolamine in sphingomyelin liposomes enhanced 2- to 10-fold the breakdown of sphingomyelin by sphingomyelinase from Bacillus cereus. On the other hand, the presence of phosphatidylcholine was either without effect or slightly stimulative at a higher molar ratio of phosphatidylcholine to sphingomyelin (3/1). In the bovine erythrocytes and their ghosts, the increase by 40-50% or the decrease by 10-23% in membranous cholesterol brought about acceleration or deceleration of enzymatic degradation of sphingomyelin by 50 or 40-50%, respectively. The depletion of ATP (less than 0.9 mg ATP/100 ml packed erythrocytes) enhanced K+ leakage from, and hot hemolysis (lysis without cold shock) of, bovine erythrocytes but decelerated the breakdown of sphingomyelin and hot-cold hemolysis (lysis induced by ice-cold shock to sphingomyelinase-treated erythrocytes), either in the presence of 1 mM MgCl2 alone or in the presence of 1 mM MgCl2 and 1 mM CaCl2. Also, ATP depletion enhanced the adsorption of sphingomyelinase onto bovine erythrocyte membranes in the presence of 1 mM CaCl2 up to 81% of total activity, without appreciable K+ leakage and hot or hot-cold hemolysis. These results suggest that the presence of cholesterol or phosphatidylethanolamine in biomembranes makes the membranes more susceptible to the attack of sphingomyelinase from B. cereus and that the segregation of lipids and proteins in the erythrocyte membranes by ATP depletion causes the deceleration of sphingomyelin hydrolysis despite the enhanced enzyme adsorption onto the erythrocyte membranes.

Adenosine Triphosphate↗
PubMed1987

Effects of phospholipases C from bacteria on binding of enkephalin to rat brain membranes.

The effects of phospholipases C on the equilibrium constants and maximal binding capacities of tritiated [D-Ala2,-D-Leu5] enkephalin to rat brain membranes were investigated using phosphatidylcholine-hydrolyzing phospholipase C and sphingomyelinase C of Bacillus cereus and, phosphatidylinositol-specific phospholipase C of Bacillus thuringiensis. When 72% of the phosphatidylinositol in the rat brain membranes was hydrolyzed by phosphatidylinositol-specific phospholipase C, the affinity of opiate receptor for [D-Ala2,-D-Leu5] enkephalin was almost doubled and maximal binding of [D-Ala2,-D-Leu5] enkephalin was decreased to 87% of control. Although specific [D-Ala2,-D-Leu5] enkephalin binding was decreased with phosphatidylinositol hydrolysis when measured at higher concentration (30 nM) of [D-Ala2,-D-Leu5] enkephalin, the specific binding was increased with the hydrolysis of phosphatidylinositol when measured at lower concentration (6 nM) of the ligand. On treatment of membranes with phosphatidylcholine-hydrolyzing phospholipase C, specific [D-Ala2,-D-Leu5] enkephalin binding was drastically decreased with the progressive hydrolysis of phosphatidylcholine in the rat brain membranes, and specific binding was completely lost after 81% hydrolysis of phosphatidylcholine. However, the affinity of opiate receptor for [D-Ala2,-D-Leu5] enkephalin was not influenced, and maximal binding was decreased to 32% of the control when 61% of phosphatidylcholine was hydrolyzed. Treatment with sphingomyelinase C did not cause any appreciable reduction of specific [D-Ala2,-D-Leu5] enkephalin binding. From these results, it is concluded that the binding of [D-Ala2,-D-Leu5] enkephalin to opiate receptor is influenced by changes in the phospholipid environment of the rat brain membranes, and that phosphatidylinositol may be a modulator for the function of the receptor.

Animals↗
PubMed1987

Properties of bovine erythrocyte acetylcholinesterase solubilized by phosphatidylinositol-specific phospholipase C1.

The properties of acetylcholinesterase solubilized from bovine erythrocyte membrane by phosphatidylinositol (PI)-specific phospholipase C of Bacillus thuringiensis or with a detergent, Lubrol-PX, were studied. The activity of Lubrol-PX-solubilized acetylcholinesterase was broadly distributed in the fractions having Ve/Vo = 1.0-2.0 in gel filtration on a Sepharose 6B column. The intermediary fractions (Ve/Vo = 1.3-1.7) were collected as "the middle active Sepharose 6B eluate" and characterized on the basis of enzymology and protein chemistry. When this eluate was treated with PI-specific phospholipase C, the major activity peak was obtained in the later fractions with Ve/Vo = 1.75-2.0 on the same column chromatography. Lubrol-solubilized and phospholipase C-treated acetylcholinesterase preparations were different in the thermostability, the elution profiles of chromatography on Mono Q, butyl-Toyopearl and phenyl-Sepharose columns, and the affinity to phospholipid micelles. On treatment with PI-specific phospholipase C, Lubrol-solubilized acetylcholinesterase became more thermostable. The phospholipase C-treated enzyme was eluted at lower NaCl concentration from the Mono Q column than the Lubrol-solubilized enzyme. The most important difference was observed in the hydrophobicity of these two enzyme preparations. The Lubrol-solubilized enzyme shows high affinity to phospholipid micelles and hydrophobic adsorbents such as butyl-Toyopearl and phenyl-Sepharose. However, this hydrophobicity was lost when acetylcholinesterase was solubilized from bovine erythrocyte membrane by PI-specific phospholipase C. The presence of myo-inositol was confirmed in the purified preparation of acetylcholinesterase by gas chromatography (GC)-mass spectrometry (MS).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1987

Effects of phospholipases C on membrane-bound enzymes of yeast.

Alkaline phosphatase was released from protoplasts of the yeast Saccharomyces cerevisiae without cell lysis not only by phosphatidylinositol (PI)-specific phospholipase C but also by phosphatidylcholine (PC)-hydrolyzing phospholipase C. Activities of mitochondrial enzymes such as succinate dehydrogenase, antimycin-sensitive NADH-cytochrome c reductase, and oligomycin-sensitive ATPase were decreased by the action of PC-hydrolyzing phospholipase C. Hydrolysis of microsomal PC or PI did not cause any decrease in the activities of NADPH-cytochrome c reductase and antimycin-insensitive NADPH-cytochrome c reductase. In the requirement of phospholipids, the properties of yeast mitochondrial enzymes were very close to those of mammalian mitochondrial enzymes, whereas those of yeast microsomal enzymes were completely different from those of mammalian microsomal enzymes.

Adenosine Triphosphatases↗
PubMed1986

Effects of phospholipases C on the beta-receptor-adenylate cyclase system of chick erythrocyte membranes.

The beta-adrenergic receptor located in chick erythrocyte membranes was characterized using (-)-[3H]-dihydroalprenolol ([3H]-DHA) with rapid filtration techniques. The affinity of beta-adrenergic antagonist, (-)-propranolol, was approximately 100-fold higher than that of (+)-propranolol. Catecholamines were bound with the receptor in the following order, (-)-isoproterenol greater than (-)-norepinephrine greater than (-)-epinephrine, suggested the binding site to be beta 1-classification. When the membrane preparation was treated with phosphatidylcholine-hydrolyzing phospholipase C (PCase) of Clostridium perfringens or phosphatidylinositol-specific phospholipase C (PIase) of Bacillus thuringiensis, [3H]-DHA binding was decreased to the level of 66 or 86% of the control, respectively. The treatment with sphingomyelinase C (SMase) of Bacillus cereus, however, did not cause any appreciable reduction of [3H]-DHA binding. Throughout these experiments, the equilibrium dissociation constant (KD) of [3H]-DHA was not influenced by phospholipases C. The affinity of isoproterenol for beta-receptor was decreased in the absence of GTP, but not altered in the presence of GTP by PIase action. Treatment with PCase or SMase, however, did not affect the affinity of isoproterenol for beta-receptor. Treatment with PIase inhibited basal, isoproterenol-stimulated and forskolin-stimulated adenylate cyclase activities. On the other hand, PCase treatment inhibited only isoproterenol-stimulated adenylate cyclase activity, but not basal and forskolin-stimulated activities. These results suggest that membrane phospholipids, especially phosphatidylcholine (PC) and phosphatidylinositol (PI), are directly related to the receptor binding and that PI interacts with adenylate cyclase activity.

Adenylyl Cyclases↗
PubMed1986

Solubilization of trehalase from rabbit renal and intestinal brush-border membranes by a phosphatidylinositol-specific phospholipase C.

Trehalase (EC 3.2.1.28) associated with renal and intestinal brush-border membranes was solubilized by highly purified phosphatidylinositol-specific phospholipase C (EC 3.1.4.10) from Bacillus thuringiensis, but not by phosphatidylcholine-hydrolyzing phospholipase C (EC 3.1.4.3) from Clostridium welchii or phospholipase D (EC 3.1.4.4) from cabbage. The solubilized trehalase was not adsorbed on phenyl-Sepharose, indicating that it was hydrophilic. Phosphatidylinositol-specific phospholipase C also converted Triton X-100-solubilized amphipathic trehalase into a hydrophilic form. These results suggest that trehalase is bound to the membrane through a direct and specific interaction with phosphatidylinositol.

Alkaline Phosphatase↗
PubMed1986

Effects of metal ions on sphingomyelinase activity of Bacillus cereus.

Some divalent metal ions were examined for their effects on sphingomyelinase activity of Bacillus cereus. The enzyme activity toward mixed micelles of sphingomyelin and Triton X-100 proved to be stimulated by Co2+ and Mn2+, as well as by Mg2+. Km's for Co2+ and Mn2+ were 7.4 and 1.7 microM, respectively, being smaller than the Km for Mg2+ (38 microM). Sr2+ proved to be a competitive inhibitor against Mg2+, with a Ki value of 1 mM. Zn2+ completely abolished the enzyme activity at concentrations above 0.5 mM. The concentration of Zn2+ causing 50% inhibition of the enzyme activity was 2.5 microM. Inhibition by Zn2+ was not restored by increasing concentrations of Mg2+ when the concentration of Zn2+ was above 10 microM. Ba2+ was without effect. When sphingomyelinase was incubated with unsealed ghosts of bovine erythrocytes at 37 degrees C, the enzyme was significantly adsorbed onto the membrane in the presence of Mn2+, Co2+, Sr2+ or Ba2+. Incubation with intact or Pronase-treated erythrocytes caused enzyme adsorption only in the presence of Mn2+. In the course of incubation, the enzyme was first adsorbed on the membranes of intact bovine erythrocytes in the presence of Mn2+; then sphingomyelin breakdown proceeded with ensuing desorption of adsorbed enzyme. Hot-cold hemolysis occurred in parallel with sphingomyelin breakdown. In this case, the hydrolysis of membranous sphingomyelin as well as the initial enzyme adsorption took place in the following order: unsealed ghosts greater than Pronase-treated erythrocytes greater than intact erythrocytes.

Animals↗
PubMed1986

Acid ATPase from chicken liver lysosomes. III. A metal ion-activated ATPase combines with membranous phosphatidylinositol.

A metal ion-activated acid ATPase was present in chicken liver lysosomes. We used Zn2+ as an activator. Lysosomal extract containing octylglucoside from chicken liver was centrifuged at 100,000 xg for 60 min. The supernatant was analyzed by gel filtration on a Sepharose 6B column. Two peaks of metal ion-activated acid ATPase activities were obtained according to the distribution patterns. Each of the two active fractions was incubated with phosphatidylinositol-specific phospholipase C at 37 degrees C for 60 min. The resulting solution was analyzed by gel filtration on a smaller size column of Sepharose 6B again. Molecular weight of the major peak was altered from approx. 1,600,000 to 130,000, whereas that of the minor one, 700,000, remained unchanged.

Adenosine Triphosphatases↗