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Biomedical subjects

Y Banno

Publications and source records attributed to Y Banno.

At least 91 records · Page 5Linked to original sources
PubMed1992

[The signal transduction of serotonin secretion involves protein tyrosine phosphorylation in rat basophilic leukemia cells].

We investigated the signal transduction of serotonin secretion by stimulation with DNP-Ascaris antigen or ionomycin in rat basophilic leukemia cells (RBL-2H3). The modes of action of antigen and ionomycin for serotonin secretion were shown to be similar. The treatment of cells with antigen resulted in increased tyrosine phosphorylation of 105 and 72 KDa proteins, in particular, the tyrosine phosphorylation of 72 KDa protein seemed to correlate with serotonin secretion. Furthermore, we observed that antigen stimulation caused a marked increase in inositol polyphosphates production, which derived from the tyrosine phosphorylation of phospholipase C-gamma in RBL-2H3 cells. On the other hand, treatment with ionomycin also resulted in an increase in tyrosine phosphorylation of 72 KDa protein, but did not induce inositol polyphosphates production. These results suggested that the activation of tyrosine kinase may be related to serotonin secretion, and that intracellular Ca2+ increase may also play an important role in this activation.

Animals↗
PubMed1991

Partial purification and characterization of two forms of phosphatidylinositol 4-phosphate 5-kinase from human platelet membrane.

The phosphatidylinositol 4-phosphate 5-kinase (PIP kinase) was isolated from the cholate extract of human platelet membranes. Two major activity peaks (PIP kinase I and PIP kinase II) were resolved by successive chromatographies on Fast Q-Sepharose, heparin-Sepharose, Mono Q and heparin-agarose columns. The PIP kinase I appears to be distinct from the PIP kinase II with regard to Mr (51 kDa and 47 kDa as determined by SDS-PAGE). The two forms of PIP kinase showed similarity in Km for ATP and Mg2+ dependency, but some differences were observed in effects of Mn2+ and phosphatidylethanolamine on the activity.

Blood Platelets↗
PubMed1991

Purification and characterization of lysophospholipase-transacylase of pathogenic fungus Candida albicans.

A lysophospholipase-transacylase was purified to homogeneity from the culture broth of Candida albicans by ammonium sulfate precipitation and chromatographs on DEAE-cellulose, Ultrogel AcA-44, first Mono Q, hydroxyapatite, TSKgel-3000 and second Mono Q columns. The purified protein was a single band (Mr 41,000) as inferred by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It had a specific activity of 78 mumol/min per mg protein for fatty acid release and 320 mumol/min per mg protein for phosphatidylcholine formation. Fatty acid release obeyed Michaelis-Menten kinetics and the apparent Km was 76 microM of 1-palmitoyl-sn-glycero-3-phosphatidylcholine, but Lineweaver-Burk plots of transacylase activity was parabolic. The ratio of hydrolase to transacylase activity of the purified enzyme was varied depending upon the concentration of lysophosphatidylcholine. Transacylation was prominent at high concentration of substrate and the ratio of hydrolase to transacylase was 0.24. Low concentration of palmitoylcarnitine (50 microM) inhibited markedly phosphatidylcholine formation but stimulated fatty acid release. The degree of esterification of 1-acyllysophosphatidylcholine was altered with mixtures of different molecular species of substrate, demonstrating acyl chain selectivity in the transfer process. These results suggest that C. albicans lysophospholipase-transacylase is different from the corresponding mammalian enzymes in enzymatic properties.

Acyltransferases↗
PubMed1991

Species-specific antibodies of Tetrahymena acid alpha-glucosidase.

1. Tetrahymena acid alpha-glucosidases A and B were purified from T. pyriformis W and T. thermophila 399, respectively. The acid alpha-glucosidases A and B were different in immunological properties and thermostability. 2. The acid alpha-glucosidases A and B reflected specific distribution between T. pyriformis and T. thermophila. 3. Type A and B of taurolipid showed a species-specific distribution pattern between T. pyriformis and T. thermophila.

Animals↗
PubMed1991

Secreted Candida albicans phospholipases: purification and characterization of two forms of lysophospholipase-transacylase.

Candida albicans secreted three types of phospholipase (lysophospholipase, lysophospholipase-transacylase and phospholipase B) at different rates in culture. Clinical isolates of C. albicans showed variable activities of these phospholipases. Two forms of lysophospholipase-transacylase (LPTA) were purified to homogeneity from the culture filtrate of C. albicans 3125. The two purified enzymes, designated LPTA-I and LPTA-II, showed some differences in molecular mass (81 kDa for LPTA-I and 41 kDa for LPTA-II), amino acid composition and enzymatic properties. Antibody raised against purified C. albicans LPTA-II reacted strongly with LPTA-II, but not with LPTA-I. Furthermore, the biochemical properties of C. albicans lysophospholipase-transacylase were distinct from those of the corresponding mammalian enzyme.

Acyltransferases↗
PubMed1990

Partial purification and characterization of phosphatidylinositol kinases from human platelets.

Most of human platelet phosphatidylinositol (PI) kinase activity (approx. 80%) was associated with the membrane fraction and its majority was released by the extraction with Triton X-100 after KCl treatment. Two major activity peaks (mPIK-I and mPIK-III) were obtained by Mono Q column chromatography. They were distinct from each other with regard to Mr (76,000 and 80,000 as determined by gel-filtration chromatography), apparent Km values for ATP, effect of arachidonic acid and phosphatidylserine and detergent requirement. Triton X-100 inhibited the activity of mPIK-I but rather weakly enhanced the mPIK-III activity, and sodium cholate remarkably inhibited both mPIK-I and mPIK-III activities. Their products were identified to be phosphatidylinositol 4-phosphate. On the other hand, about 20% of PI kinase activity was recovered from the cytosolic fraction and two activity peaks (cPIK-I and cPIK-II) were resolved on Mono Q column chromatography. There were no significant differences in biochemical properties between cPIK-I and cPIK-II. Both of them had Mr approx. 550,000 as determined by gel-filtration chromatography and were activated by sodium cholate to a greater extent than by Triton X-100. The results suggest that the major PI kinases (mPIK-I and mPIK-III) are PI 4-kinase and mPIK-I is distinct from PI 4-kinases in other sources especially with regard to the effect of Triton X-100.

1-Phosphatidylinositol 4-Kinase↗
PubMed1990

Purification and characterization of a cytosolic phosphoinositide-phospholipase C (gamma 2-type) from human platelets.

A human platelet cytosolic phosphoinositide-specific phospholipase C, one of four PLC activity peaks separated by column chromatographies, designated as cPLC-I, was purified to homogeneity. The cPLC-I exhibited an apparent Mr of 145 kDa by SDS-polyacrylamide gel electrophoresis and was immunologically identified to be PLC-gamma 2. It hydrolyzed PI and PIP2 at optimum pH of 5.5-6.0. Deoxycholate and cholate inhibited the enzyme activity to hydrolyze two substrates. Calcium was required to obtain the maximal activity for PI- and PIP2-hydrolysis at concentration of 10(-3) M and 10(-5) M, respectively. Hg2+ (1 microM) inhibited strongly the enzyme activity.

Blood Platelets↗
PubMed1989

Studies into hormonal imprinting in a Tetrahymena thermophila mutant incapable of lysosomal enzyme secretion.

Reexposure to insulin after primary interaction (hormonal imprinting) was followed by a binding increase in T. pyriformis and by a binding decrease in T. thermophila. The sec. mutant, MS-1 strain of T. thermophila, which is unable of lysosomal enzyme secretion, also showed a binding increase on a second exposure to insulin, from which it follows that alteration of the enzyme secretion, or other factors associated with mutation, accounted for reversion of the trend of imprinting. Thyrotropic hormone (TSH) also gave rise to a negative imprinting in T. thermophila, but did not alter the binding relations of the MS-1 mutant strain.

Animals↗
PubMed1988

Purification and characterization of membrane-bound phospholipase C specific for phosphoinositides from human platelets.

Two peaks (mPLC-I and mPLC-II) of phosphatidylinositol 4,5-bisphosphate (PIP2)-hydrolyzing activity were resolved when 1% sodium cholate extract from particulate fractions of human platelet was chromatographed on a heparin-Sepharose column. The major peak of enzyme activity (mPLC-II) was purified to homogeneity by a combination of Fast Q-Sepharose, heparin-Sepharose, Ultrogel AcA-44, Mono Q, Superose 6-12 combination column, and Superose 12 column chromatographies. The specific activity increased 2,700-fold as compared with that of the starting particulate fraction. The purified mPLC-II had an estimated molecular weight of 61,000 on sodium dodecyl sulfate-polyacrylamide gels. The minor peak of enzyme activity (mPLC-I) was partially purified to 430-fold. Both enzymes hydrolyzed PIP2 at low Ca2+ concentration (0.1-10 microM) and exhibited higher Vmax for PIP2 than for phosphatidylinositol. PIP2-hydrolyzing activities of both enzymes were enhanced by various detergents and lipids, such as deoxycholate, cholate, phosphatidylethanolamine, and dimyristoylphosphatidylcholine. The mPLC-I and mPLC-II activities were increased by Ca2+, but not by Mg2+, while Hg2+, Fe2+, Cu2+, and La3+ were inhibitory. GTP-binding proteins (Gi, Go, and Ki-ras protein) had no significant effects on the mPLC-II activity.

Blood Platelets↗
PubMed1988

Regional distribution of phosphoinositide-specific phospholipase C activity in rat brain.

The phosphatidylinositol (PI) and phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolytic activities of phosphoinositide-specific phospholipase C (PLC) were measured in membrane and cytosol fractions from 7 discrete areas of the rat brain. Both the PI-PLC and PIP2-PLC specific activities were found to differ significantly among the 7 discrete brain areas. In the membrane fraction, the PIP2-PLC activity was higher than that of PI-PLC in each region, suggesting that the PLC in membranes prefers PIP2 to PI as substrate. The PIP2-PLC activities in the membrane were high in prefrontal cortex and cerebellum, but rather low in medulla oblongata and hypothalamus. The PI-PLC specific activity in the cytosol was significantly higher than that in the membrane of all brain areas examined. The PI-PLC specific activity in membranes is inversely proportional to its activity in the cytosol. In the cytosol fraction, the distribution pattern of PI-PLC specific activity resembled that of PIP2-PLC. These results indicate that PLCs are differently distributed in various regions of rat brain, and suggest the regional differences in neuronal transduction.

Animals↗
PubMed1987

Characterization of partially purified phospholipase C from human platelet membranes.

A phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]-hydrolytic activity was found to be present in the human platelet membrane fraction, with 20% of the total activity of the homogenate. The membrane-associated phospholipase C activity was extracted with 1% deoxycholate (DOC). The DOC-extractable phospholipase C was partially purified approx. 126-fold to a specific activity of 0.58 mumol of PtdIns-(4,5)P2 cleaved/min per mg of protein, by Q-Sepharose, heparin-Sepharose and Ultrogel AcA-44 column chromatographies. This purified DOC-extractable phospholipase C had an Mr of approx. 110,000, as determined by Ultrogel AcA-44 gel filtration. The enzyme exhibits a maximal hydrolysis for PtdIns-(4,5)P2 at pH 6.5 in the presence of 0.1% DOC. The addition of 0.1% DOC caused a marked activation of both PtdIns(4,5)P2 and phosphatidylinositol (PtdIns) hydrolyses by the enzyme. The enzyme hydrolysed PtdIns(4,5)P2 and PtdIns in a different Ca2+-dependent manner; the maximal hydrolyses for PtdIns(4,5)P2 and PtdIns were obtained at 4 microM- and 0.5 mM-Ca2+ respectively. In the presence of 1 mM-Mg2+, PtdIns(4,5)P2-hydrolytic activity was decreased at all Ca2+ concentrations examined, but PtdIns-hydrolytic activity was not affected.

Blood Platelets↗