Search results for " trip"

Structural insights into the GTPase domain of Escherichia coli MnmE protein

2007

The Escherichia coli MnmE protein is a 50-kDa multidomain GTPase involved in tRNA modification. Its homologues in eukaryotes are crucial for mitochondrial respiration and, thus, it is thought that the human protein might be involved in mitochondrial diseases. Unlike Ras, MnmE shows a high intrinsic GTPase activity and requires effective GTP hydrolysis, and not simply GTP binding, to be functionally active. The isolated MnmE G-domain (165 residues) conserves the GTPase activity of the entire protein, suggesting that it contains the catalytic residues for GTP hydrolysis. To explore the GTP hydrolysis mechanism of MnmE, we analyzed the effect of low pH on binding and hydrolysis of GTP, as well…

Structural and Functional Basis for Understanding the Biological Significance of P2X7 Receptor

2020

The P2X7 receptor (P2X7R) possesses a unique structure associated to an as yet not fully understood mechanism of action that facilitates cell permeability to large ionic molecules through the receptor itself and/or nearby membrane proteins. High extracellular adenosine triphosphate (ATP) levels—inexistent in physiological conditions—are required for the receptor to be triggered and contribute to its role in cell damage signaling. The inconsistent data on its activation pathways and the few studies performed in natively expressed human P2X7R have led us to review the structure, activation pathways, and specific cellular location of P2X7R in order to analyze its biological relevance. The ATP-…

8-N(3)-3'-biotinyl-ATP, a novel monofunctional reagent: differences in the F(1)- and V(1)-ATPases by means of the ATP analogue.

2001

A novel photoaffinity label, 8-N(3)-3'-biotinyl-ATP, has been synthesized. The introduction of an additional biotin residue is advantageous for easy detection of labeled proteins. This could be first tested by reaction with the F(1)-ATPase from the thermophilic bacterium PS3 (TF(1)). UV irradiation of TF(1) in the presence of 8-N(3)-3'-biotinyl-ATP results in a nucleotide-dependent binding of the analogue in the noncatalytic alpha and the catalytic beta subunits of TF(1), demonstrating the suitability of this analogue as a potential photoaffinity label. Reaction with the V(1)-ATPase, however, led to labeling of subunit E, which has been suggested as a structural and functional homologue of …

The nuclear autoantigen La/SS-associated antigen B: One gene, three functional mRNAs

1997

Transcription of the gene encoding for the nuclear autoantigen La resulted in three mRNA forms. A promoter switching combined with an alternative splicing pathway replaced exon 1 with either exon 1´ or exon 1´´. The exon 1´´ donor splice site was located 4 nts downstream of the exon 1´ donor splice site. All three La mRNA forms were expressed in all the tissues analysed including peripheral blood lymphocytes, liver, fetal spleen, cultured primary endothelial cells, and mouse LTA cell lines permanently transfected with the human La gene. Both the exons 1´ and 1´´ had unusual structures. They contained GC-rich regions and an oligo(U)-tail of 23 uridine residues. Moreover, they encoded for thr…

Mapping of a binding site for ATP within the extracellular region of the Torpedo nicotinic acetylcholine receptor beta-subunit.

1997

Using 2,8,5'-[H-3]ATP as a direct photoaffinity label for membrane-bound nicotinic acetylcholine receptor (nAChR) from Torpedo marmorata, we have identified a binding site for ATP in the extracellular region of the beta-subunit of the receptor. Photolabeling was completely inhibited in the presence of saturating concentrations of nonradioactive ATP, whereas neither the purinoreceptor antagonists suramin, theophyllin, and caffeine nor the nAChR antagonists alpha-bungarotoxin and d-tubocurarine affected the labeling reaction. Competitive and noncompetitive nicotinic agonists and Ca2+ increased the yield of the photoreaction by up to 50%, suggesting that the respective binding sites are allost…

Inhibition of Eimeria tenella CDK-related kinase 2: From target identification to lead compounds.

2010

Apicomplexan parasites encompass several human- and animal-pathogenic protozoans such as Plasmodium falciparum, Toxoplasma gondii, and Eimeria tenella. E. tenella causes coccidiosis, a disease that afflicts chickens, leading to tremendous economic losses to the global poultry industry. The considerable increase in drug resistance makes it necessary to develop new therapeutic strategies against this parasite. Cyclin-dependent kinases (CDKs) are key molecules in cell-cycle regulation and are therefore prominent target proteins in parasitic diseases. Bioinformatics analysis revealed four potential CDK-like proteins, of which one—E. tenella CDK-related kinase 2 (EtCRK2)—has already been charact…

Turismo e mobilità: aspetti di ricerca e principali implicazioni per le statistiche del turismo

2010

NF-κB is a potential pharmacological target in triple negative breast cancers.

2015

Triple negative breast cancers (TNBCs), characterized by lack of estrogen, progesterone and HER2 receptors, are a highly heterogenous group of tumors which account for about 20% to 25% of all breast cancers. TNBCs are often associated with epithelial-mesenchymal transition and a high propensity for early metastasis. Since no molecularly-targeted therapeutic agents are clinically available for TNBCs, these tumors, which are frequently resistant to cytotoxic chemotherapy, remain difficult to treat. Nevertheless, progress is being made in the finding of molecular alterations typical of TNBCs toward which to focus therapeutic efforts.

Synthesis of the new ring system pyrrolizino[2,3-b]indol-4(5H)-one

2011

Derivatives of the new ring system pyrrolizino[2,3-b]indol-4(5H)-one were prepared in four steps starting from substituted benzonitriles bearing a functionalized amino group in the adjacent position. The unsubstituted- and the dimethoxy-pyrrolizinoindolones 5a and 5b exhibited modest activity against the HL-60(TB) human leukemia cell line, whereas the N-methylated dimethoxy-pyrrolizinoindolone 6b showed to be selective against MOLT-4 leukemia, A549/ATCC, HOP-92, and NCI-H460 non-small cell lung cancer, and CAKI-1 renal cancer cell lines.

NANC inhibitory neurotransmission in mouse isolated stomach: Involvement of nitric oxide, ATP and vasoactive intestinal polypeptide

2003

1. The neurotransmitters involved in NANC relaxation and their possible interactions were investigated in mouse isolated stomach, recording the motor responses as changes of endoluminal pressure from whole organ. 2. Field stimulation produced tetrodotoxin-sensitive, frequency-dependent, biphasic responses: rapid transient relaxation followed by a delayed inhibitory component. 3. The inhibitor of the synthesis of nitric oxide (NO), L-NAME, abolished the rapid relaxation and significantly reduced the slow relaxation. Apamin, blocker of Ca 2+-dependent K + channels, or ADPβS, which desensitises P 2y purinoceptors, reduced the slow relaxation to 2-8 Hz, without affecting that to 16-32 Hz or the…