Search results for "tPA"
showing 10 items of 770 documents
An Arabidopsis Mutant Over-Expressing Subtilase SBT4.13 Uncovers the Role of Oxidative Stress in the Inhibition of Growth by Intracellular Acidificat…
2020
Intracellular acid stress inhibits plant growth by unknown mechanisms and it occurs in acidic soils and as consequence of other stresses. In order to identify mechanisms of acid toxicity, we screened activation-tagging lines of Arabidopsis thaliana for tolerance to intracellular acidification induced by organic acids. A dominant mutant, sbt4.13-1D, was isolated twice and shown to over-express subtilase SBT4.13, a protease secreted into endoplasmic reticulum. Activity measurements and immuno-detection indicate that the mutant contains less plasma membrane H+-ATPase (PMA) than wild type, explaining the small size, electrical depolarization and decreased cytosolic pH of the mutant but not orga…
Immunological detection of tonoplast polypeptides in the plasma membrane of pea cotyledons
1996
The tonoplast is usually characterized by the presence of two electrogenic proton pumps: a vacuolartype H+-ATPase and a pyrophosphatase, as well as a putative water-channel-forming protein (γ-TIP). Using a post-embedding immunogold labelling technique, we have detected the presence of these transport-protein complexes not only in the tonoplast, but also in the plasma membrane and trans Golgi elements of maturing pea (Pisum sativum L.) cotyledons. These ultrastructural observations are supported by Western blotting with highly purified plasma-membrane fractions. In contrast to the vacuolar-type H+-ATPase, whose activity was not measurable, considerable pyrophosphatase activity was detected i…
Arbuscular mycorrhiza induced ATPases and membrane nutrient transport mechanisms
2002
The evolutionary success of arbuscular mycorrhizal (AM) symbiosis reflects the unique combination of a superior biotrophic mode of fungal carbon acquisition and the ability of the living plant to absorb nutrients, especially phosphorus, from the fungal partner (Jakobsen 1999). This mutualistic way of life must require controlled expression of a large set of membrane transport systems active in phosphate uptake from the soil by the extraradical hyphae, its transfer to the host plant across a symbiotic interface, and coupled to transport of photosynthates in the opposite direction. The implied membrane transporters are therefore integral systems in the functioning of the symbiosis. Very littl…
Activation of the plant plasma membrane H+ -ATPase. Is there a direct interaction between lysophosphatidylcholine and the C-terminal part of the enzy…
1996
The antagonistic effects of the fungal toxin beticolin-1 and of L-alpha-lysophosphatidylcholine (lysoPC) were investigated on the plasma membrane H+-ATPase of the plant Arabidopsis thaliana (isoform 2) expressed in yeast, using both wild-type enzyme (AHA2) and C-terminal truncated enzyme (aha2delta92). Phosphohydrolytic activities of both enzymes were inhibited by beticolin-1, with very similar 50% inhibitory concentrations, indicating that the toxin action does not involve the C-terminal located autoinhibitory domain of the proton pump. Egg lysoPC, a compound that activates the H+-ATPase by a mechanism involving the C-terminal part of the protein, was found to be able to reverse the inhibi…
Identification and molecular characterization of the high-affinity copper transporters family in Solanum lycopersicum
2021
Copper (Cu) plays a key role as cofactor in the plant proteins participating in essential cellular processes, such as electron transport and free radical scavenging. Despite high-affinity Cu transporters (COPTs) being key participants in Cu homeostasis maintenance, very little is known about COPTs in tomato (Solanum lycopersicum) even though it is the most consumed fruit worldwide and this crop is susceptible to suboptimal Cu conditions. In this study, a six-member family of COPT (SlCOPT1-6) was identified and characterized. SlCOPTs have a conserved architecture consisting of three transmembrane domains and β-strains. However, the presence of essential methionine residues, a methionine-enri…
Functional reconstitution of a proton-translocating system responsive to fusicoccin
1988
Crude fusicoccin binding proteins and a partially purified plasma membrane H+-transporting ATPase (EC 3.6.1.34), both solubilized from maize tissues, were simultaneously inserted into liposomes by the freeze-thaw method. ATP-driven intravesicular acidification in the proteoliposomes, measured by the fluorescence quenching of the dye 9-amino-6-chloro-2-methoxyacridine, markedly increased upon addition of fusicoccin to the reconstituted system. This effect could not be observed when binding sites and ATPase preparations were separately reconstituted into the proteoliposomes, thus demonstrating that fusicoccin binding to its receptor is a prerequisite for ATPase stimulation.
Cercospora beticola toxins. Use of fluorescent cyanine dye to study their effects on tobacco cell suspensions
1996
Abstract The fluorescent dye 3,3′-diethylthiadicarbocyanine iodide [diS-C 2 -(5)] was used to observe plasmalemma transmembrane potential variations of tobacco cells treated with uncoupler (FCCP), respiratory inhibitors (azide and cyanide), and H + -ATPase inhibitors (DCCD and a carbanilate derivative). These chemicals induced an increase in fluorescence, indicating a dissipation of the transmembrane potential. The [diS-C 2 -(5)] was also used to study the effects of two Cercospora beticola toxins on tobacco cells. Changes in fluorescence of [diS-C 2 -(5)] suggested that these two toxins caused a dissipation of the transmembrane potential with a different magnitude whereas kinetics of their…
Ultrastructure of regions containing homologous loci in polytene chromosomes of Drosophila melanogaster and Drosophila subobscura.
1998
We have used a new approach involving in situ hybridisation and electron microscopy to establish ultrastructural homologies between polytene chromosome regions of Drosophila melanogaster and Drosophila subobscura. Twelve probes were chosen to cover all the chromosomal elements: the myospheroid gene, the collagen type IV gene, the collagen-like gene, the w26 homeobox gene, the beta3 tubulin gene, the kinesin heavy chain gene, the tryptophan hydrolase gene, the Hsp82, Hsp22-26 and Hsp23-28, Hsp68, Hsp70 genes and the beta unit of the F0-F1 ATPase gene. Most of these loci were previously undescribed in D. subobscura and imprecisely located in D. melanogaster. We have demonstrated here, by an u…
Nitric Oxide in Plants: Production and Cross-talk with Ca2+ Signaling
2008
International audience; Nitric oxide (NO) is a diatomic gas that performs crucial functions in a wide array of physiological processes in animals. The past several years have revealed much about its roles in plants. It is well established that NO is synthesized from nitrite by nitrate reductase (NR) and via chemical pathways. There is increasing evidence for the occurrence of an alternative pathway in which NO production is catalysed from L-arginine by a so far non-identified enzyme. Contradictory results have been reported regarding the respective involvement of these enzymes in specific physiological conditions. Although much remains to be proved, we assume that these inconsistencies can …
Characterization of a proton pump from Acer pseudoplatanus cell microsomes
1985
Abstract An Acer pseudoplatanus cell microsomal fraction was enriched in ATPase by sedimentation through a sucrose cushion and treatment with Triton X-100. This activity, which reached 0.9 μmol P i min −1 mg −1 protein, was specific for ATP, slightly stimulated by K + , inhibited by orthovanadate and diethylstilbestrol, insensitive to oligomycin and azide, and had a K m - value of 0.51 mM for MgATP. ATP-dependent proton translocation was demonstrated by the ΔpH probe acridine orange. This activity had a optimum at pH 6.5, was substrate specific for ATP, and was strongly dependent on K + . Preparations of plasma membrane ATPase from A. pseudoplatanus cell culture thus posses biochemical prop…