Search results for "P'"
showing 10 items of 80 documents
Restoration of Clostridium difficile toxin-B-inhibited phospholipase D by phosphatidylinositol 4,5-bisphosphate.
1996
Receptor signalling to phospholipase D (PLD) in human embryonic kidney (HEK) cells stably expressing the m3 muscarinic acetylcholine receptor apparently involves Rho proteins. Since phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] has been recognized as an essential cofactor for PLD activity and since activated Rho proteins have been reported to stimulate the synthesis of PtdIns(4,5)P2, we studied whether in HEK cells PLD activity is regulated by PtdIns(4,5)P2 and, in particular, whether PtdIns(4,5)P2 can restore PLD activity inhibited by Clostridium difficile toxin B, which inactivates Rho proteins. Addition of MgATP to permeabilized HEK cells increased basal PLD activity and potentia…
Differential changes in purine nucleotides after Doxorubicin treatment of human cancer cells in vitro
2002
The present investigation was performed to elucidate the role of purine nucleotides as potential indicators of chemosensitivity of malignant tumors. Drug-sensitive (s) and -resistant (r) tumor cell lines grown as monolayers (s: T47D, MCF-7 wild-type; r: NCI/ADR-RES, MCF-7/MDR) or as multicellular spheroids (T47D; NCI/ADR-RES) were exposed to 0.1, 1.0, and 10.0 microM Doxorubicin for up to 24 h. Purine nucleotides were assayed using HPLC and with some selected spheroids using imaging bioluminescence. The data show that in the time frame of the experiments reproducible and statistically significant changes in the nucleotides only occur at the highest drug concentration investigated. Under the…
Nucleotide pool changes in coelomic cells (eleocytes) of the polychaete Nereis virens during sexual maturation
1998
Eleocytes (a type of coelomic cell) of the polychaete Nereis virens can store large amounts of adenine nucleotides at certain times. Since eleocytes have specific functions related to gametogenesis, we tested whether the presence of these large nucleotide stores in eleocytes is specific to gender or related to specific events during gametogenesis. Nucleotide pools in eleocytes isolated at different stages of sexual maturation from N. virens were analysed using high-performance liquid chromatography. Eleocytes from immature and male animals had extremely high concentrations of both AMP and ADP (each > 10 µmol/ml of packed cell volume). In eleocytes from male animals, the high nucleotide stor…
Antagonistic feedback loops involving Rau and Sprouty in the Drosophila eye control neuronal and glial differentiation.
2013
During development, differentiation is often initiated by the activation of different receptor tyrosine kinases (RTKs), which results in the tightly regulated activation of cytoplasmic signaling cascades. In the differentiation of neurons and glia in the developing Drosophila eye, we found that the proper intensity of RTK signaling downstream of fibroblast growth factor receptor (FGFR) or epidermal growth factor receptor required two mutually antagonistic feedback loops. We identified a positive feedback loop mediated by the Ras association (RA) domain-containing protein Rau that sustained Ras activity and counteracted the negative feedback loop mediated by Sprouty. Rau has two RA domains t…
The GTP- and Phospholipid-Binding Protein TTD14 Regulates Trafficking of the TRPL Ion Channel in Drosophila Photoreceptor Cells
2015
Recycling of signaling proteins is a common phenomenon in diverse signaling pathways. In photoreceptors of Drosophila, light absorption by rhodopsin triggers a phospholipase Cβ-mediated opening of the ion channels transient receptor potential (TRP) and TRP-like (TRPL) and generates the visual response. The signaling proteins are located in a plasma membrane compartment called rhabdomere. The major rhodopsin (Rh1) and TRP are predominantly localized in the rhabdomere in light and darkness. In contrast, TRPL translocates between the rhabdomeral plasma membrane in the dark and a storage compartment in the cell body in the light, from where it can be recycled to the plasma membrane upon subsequ…
Role of glycine-82 as a pivot point during the transition from the inactive to the active form of the yeast Ras2 protein
1991
AbstractRas proteins bind either GDP or GTP with high affinity. However, only the GTP-bound form of the yeast Ras2 protein is able to stimulate adenylyl cyclase. To identify amino acid residues that play a role in the conversion from the GDP-bound to the GTP-bound state of Ras proteins, we have searched for single amino acid substitutions that selectively affected the binding of one of the two nucleotides. We have found that the replacement of glycine-82 of the Ras2 protein by serine resulted in an increased rate of dissociation of Gpp(NH)p, a nonhydrolysable analog of GTP, while the GDP dissociation rate was not significantly modified. Glycine-82 resides in a region that is highly conserve…
Phosphorylation of an Overexpressed Yeast Ras2 Protein During the G1 Phase of the Cell Cycle
1994
RAS proteins regulate growth and differentiation in evolutionarily distant systems such as vertebrates and yeast (for reviews, see Tamanoi, 1988; Gibbs and Marshall, 1989; Broach and Deschenes, 1990). At the moleular level, a key function of the yeast RAS1 and RAS2 proteins (collectively referred to as RAS) is to positively regulate the production of cyclic AMP at the onset of the G1 phase of the cell cycle (Toda et al., 1985; De Vendittis et al., 1986). At this stage, RAS proteins are transiently activated by the noncovalent binding of a GTP molecule. Reversal of the effect occurs by the hydrolytic splitting of the ’γ-phosphate of GTP, that leaves a functionally inactive RASGDP complex, th…
CCDC 802648: Experimental Crystal Structure Determination
2011
Related Article: R.D.Costa, D.Tordera, E.Orti, H.J.Bolink, J.Schonle, S.Graber, C.E.Housecroft, E.C.Constable, J.A.Zampese|2011|J.Mater.Chem.|21|16108|doi:10.1039/c1jm12607e
CCDC 697120: Experimental Crystal Structure Determination
2009
Related Article: M.Ciclosi, F.Estevan, P.Lahuerta, V.Passarelli, J.Perez-Prieto, M.Sanau|2009|Dalton Trans.||2290|doi:10.1039/b816185b
CCDC 216064: Experimental Crystal Structure Determination
2005
Related Article: I.Rojo, F.Teixidor, C.Vinas, R.Kivekas, R.Sillanpaa|2004|Chem.-Eur.J.|10|5376|doi:10.1002/chem.200400361