The PDZ2 domain of zonula occludens-1 and -2 is a phosphoinositide binding domain

Zonula occludens proteins (ZO) are postsynaptic density protein-95 discs large-zonula occludens (PDZ) domain-containing proteins that play a fundamental role in the assembly of tight junctions and establishment of cell polarity. Here, we show that the second PDZ domain of ZO-1 and ZO-2 binds phosphoinositides (PtdInsP) and we identified critical residues involved in the interaction. Furthermore, peptide and PtdInsP binding of ZO PDZ2 domains are mutually exclusive. Although lipid binding does not seem to be required for plasma membrane localisation of ZO-1, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P ₂) binding to the PDZ2 domain of ZO-2 regulates ZO-2 recruitment to nuclear speckles. Knockdown of ZO-2 expression disrupts speckle morphology, indicating that ZO-2 might play an active role in formation and stabilisation of these subnuclear structures. This study shows for the first time that ZO isoforms bind PtdInsPs and offers an alternative regulatory mechanism for the formation and stabilisation of protein complexes in the nucleus.     

Interaction of sulfonylurea with the pancreatic B-cell

Conclusions Sulfonylureas have a variety of effects on pancreatic B-cells. In the present review an attempt has been made to identify those that appear fundamental from a mechanistic point of view and in that sense common to all hypoglycemic drugs tested. On several points the available able experimental information is limited. With this reservation in mind, the following general hypothesis is presented for the insulin-releasing action of this class of drugs. Hypoglycemic sulfonylureas and related [(acylamino)alkyl]benzoic acids bind to the B-cell plasma membrane, a step in which hydrophobic anchoring is essential. Dissociated acidic COOH or SO₂NHCO groups in the drugs are thus presented to an ion-gating protein in the plasma membrane, possibly in the vicinity of a pair of sulfur atoms. The reduced state of these sulfurs is promoted, preventing the formation of a disulfide bridge. K⁺ permeability is thereby decreased, favoring depolarization of the B-cell and Ca²⁺ influx through voltage-dependent channels. Finally, Ca²⁺ triggers the physiological apparatus for discharge of the insulin secretory granules. The effect of this insulinreleasing signal chain is amplified by cyclic AMP which increases in the B-cell as a consequence of depolarization and Ca²⁺ influx. This hypothesis does not attribute an ionophoretic role to the sulfonylureas per sebecause various experiments with cells and artificial membrane systems render such an idea apparently less tenable.     

Interaction of 1-anilino-8-naphthalene sulfonate with yeast glyceraldehyde-3-phosphate dehydrogenase

1--8- () -3- () . []:[]<10:1 140 000 3±1 5×10^–5 . , i 5×10^–5 –6×10^–5 M. , .     

Interaction of pepsin with lysozyme

Riassunto L'autore ha studiato il complesso che si forma dall'interazione della pepsina con il lisozima.Vengono riferiti i risultati ottenuti studiando le caratteristiche torbidimetriche, elettroforetiche e di sedimentazione all'ultracentrifuga del complesso pepsinalisozima.Il complesso ha il punto isoelettrico a pH 7.3, ed ha una costante di sedimentazioneS ₂₀=4.9×10^–13.     

Interaction of lead with erythrocytes

Zusammenfassung Untersuchungen mit²⁰³Pb in vitro ergeben, dass Blei in den Erythrozyten vorwiegend an Hämoglobin gebunden wird, während Stromasubstanzen kein Blei aufnehmen.     

Interaction of glutaraldehyde with some micro-organisms

Résumé La glutaraldéhyde produit une couleur rouge chez quelques genres de bactéries. Cette couleur est prise par la paroi cellulaire des organismes.     

Interaction of vinblastine analogues with tubulin

Summary Studies of the interaction between vinblastine-like alkaloids and their receptor, i.e. tubulin, are reported. They shed some light on the structure-activity relationships in this medicinally important series: the configurations at C₁₄ and C₁₆ as well as the presence of the methoxycarbonyl group on C₁₆ seem to play an essential role in the determination of biological activity.This work was supported by CNRS (A.T.P. No 3232).We thank Dr D. Pantaloni for interesting discussions, Drs N. and Y. Langlois for discussions and for supplying synthetic material, and Eli Lilly Laboratories for gifts of vinblastine, vincristine and leurosidine.     

Interaction of platinum compounds with bacterial DNA

Summary The cis and trans isomer of PtCl₂(NH₃)₂, cis-Pt(cpa)₂Cl₂ and 2 platinum pyrimidine blues have been used in a number of bacterial tests indicative of their interaction with bacterial DNA.This investigation was supported by a grant from C.N.R., Rome. We thank Mrs S. Saincich for skilful technical assistance.     

Interaction of mitochondrial porin with cytosolic proteins

Summary Intracellular phosphorylation is an important step in active uptake and utilization of carbohydrates. For example glucose and glycerol enter the liver, cell along the extra intracellular gradient by facilitated diffusion through specific carriers and are concentrated inside the cell by phosphorylation via hexokinase or glycerol kinase. Depending on the function of the respective tissue the uptake of carbohydrates serves different metabolic purposes. In brain and kidney medulla cells which depend on carbohydrates, glucose and glycerol are taken up according to the energy demand. However, in tissues such as muscle which synthesize glycogen or like liver which additionally produce fat from glucose, the uptake of carbohydrates has to be regulated according to the availability of glucose and glycerol. How the reversible coupling of the kinases to the outer membrane pore and the mitochondrial ATP serves to fulfil these specific requirements will be explained as well as how this regulates the carbohydrate uptake in brain according to the activity of the oxidative phosphorylation and how this allows glucose uptake in liver, and muscle to persist in the presence of high glucose 6-phosphate without activating the rate of glycolysis.     

Interaction of mammalian hemoglobins with dehydroascorbic acid

Summary Reactive sulfhydryl groups of major hemoglobins from guinea-pig, rat and cat reduced dehydroascorbic acid to ascorbic acid leading to formation of intrachain disulfide bonds. Hybridization experiments indicated that the reduction was carried out by thea chain of cat hemoglobin.This work was supported in part by UGC and a DST grant HCS/DST/258/76.     

Interaction of basic dyes with the thiamine transport system inSaccharomyces cerevisiae

Summary Basic dyes such as methylene blue and triphenyltetrazolium chloride were found to inhibit thiamine transport inSaccharomyces cerevisiae. Conversely, the reduction of methylene blue and triphenyltetrazolium chloride by yeast cells was inhibited by thiamine. A thiamine transport mutant ofSaccharomyces cerevisiae showed decreased utilization of these dyes. From the results, the possibility that the uptake of basic dyes may proceed via a membrane-bound thiamine-binding protein in the thiamine transport system of the yeast is discussed.This work was supported in part by a grant from the Ministry of Education, Science and Culture of Japan.     

Interaction of mitochondrial porin with cytosolic proteins.

Intracellular phosphorylation is an important step in active uptake and utilization of carbohydrates. For example glucose and glycerol enter the liver cell along the extra intracellular gradient by facilitated diffusion through specific carriers and are concentrated inside the cell by phosphorylation via hexokinase or glycerol kinase. Depending on the function of the respective tissue the uptake of carbohydrates serves different metabolic purposes. In brain and kidney medulla cells which depend on carbohydrates, glucose and glycerol are taken up according to the energy demand. However, in tissues such as muscle which synthesize glycogen or like liver which additionally produce fat from glucose, the uptake of carbohydrates has to be regulated according to the availability of glucose and glycerol. How the reversible coupling of the kinases to the outer membrane pore and the mitochondrial ATP serves to fulfil these specific requirements will be explained as well as how this regulates the carbohydrate uptake in brain according to the activity of the oxidative phosphorylation and how this allows glucose uptake in liver and muscle to persist in the presence of high glucose 6-phosphate without activating the rate of glycolysis.     

Interaction of galectin-1 with caveolae induces mouse embryonic stem cell proliferation through the Src, ERas, Akt and mTOR signaling pathways

Galectins have the potential to provide a promising alternative for unveiling the complexity of embryonic stem (ES) cell self-renewal, although the mechanism by which galectins maintain ES cell self-renewal has yet to be identified. Galectin-1 increased [³H]-thymidine incorporation as well as cyclin expression and decreased p27^kip1 expression. Src and caveolin-1 phosphorylation was increased by galectin-1, and phospho-caveolin-1 was inhibited by PP2. In addition, inhibition of caveolin-1 by small interfering RNA and methyl-β-cyclodextrin (Mβ-CD) decreased galectin-1-induced cyclin expression and [³H]-thymidine incorporation. Galectin-1 caused Akt and mTOR phosphorylation, which is involved in cyclin expression. Galectin-1-induced phospho-Akt and -mTOR was inhibited by PP2, ERas siRNA, caveolin-1 siRNA and Mβ-CD. Furthermore, mTOR phosphorylation was decreased by LY294002 and Akt inhibitor. Galectin-1-induced increase in cyclin expression and decrease in p27^kip1 was blocked by Akt inhibitor and rapamycin. In conclusion, galectin-1 increased DNA synthesis in mouse ES cells via Src, caveolin-1 Akt, and mTOR signaling pathways. Received 30 October 2008; received after revision 18 February 2009; accepted 24 February 2009     

Interaction of molybdate with copper(II)-histidine

Summary Molybdate and copper(II)-histidine form an insoluble complex of empirical formula Cu₂(His)₃(MoO₄)₂(H₂O)₂. ESR-spectroscopy indicated that the complex had tetragonal symmetry. IR-spectroscopy showed the presence of a carboxylate anion and suggested that the molybdate ion formed an ammonium-type salt with the nitrogens of the imidazole. The complex did not form following dissociation of the protonated imidazole (above a pH of approximately 6).Acknowledgments. Drs C. Tennant, D. McGavin and B. Cleverly, Chemistry Division, D.S.I.R., Petone, for the computer simulated ESR spectrum and for help in interpreting ESR- and IR-spectra; Prof. A. D. Campbell, Department of Chemistry, University of Otago, Dunedin, for C,H,N- and H₂O-microanalyses.     

Interaction of DEAE-dextran with mammalian cells cultivated in vitro

Zusammenfassung Wachstum, morphologische Eigenschaften und Karyotypie kultivierter L-Zellen wurden nach Applikation von DEAE-Dextran im Inkubations-medium untersucht. In einer Konzentration von 500 g/ml (was die Aufnahme von exogener DNS fördert) und bei einer Einwirkung während 30 min verändert DEAE-Dextran die untersuchten Eigenschaften nicht.