PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 8185718

[Why do endothelial cells require adenosine triphosphate?].

J Schrader·M Gruwel·U Decking·C Alves
View original source ↗Export metadata ↓

Abstract

NMR-spectroscopy (31P-NMR, 23Na-NMR) has been used to characterize the energy metabolism of cultured endothelial cells of the pig aorta and to determine the energy requirements of the Na-K-ATPase relative to total cellular energy consumption. Endothelial cells exhibited high concentrations of creatine phosphate and cardiac microvascular creatine kinase (CK) was of the BB-CK subtype. BB-CK can therefore be used as a marker-enzyme of endothelial cells in muscular organs. The transmembrane flux-rate of sodium was 117 mumol Nalmin/mg prot in the steady state at an intracellular sodium concentration of 25 mmol/l. Combining microcalorimetric measurements with 23Na-NMR data revealed that the energy requirement of endothelial Na-K-ATPase despite the high surface to volume ratio comprises only 3-5% of total cellular energy consumption.

Explore related subjects

Adenosine TriphosphateAnimalsEndothelium, VascularEnergy MetabolismHumansSodium-Potassium-Exchanging ATPaseSwineJournal ArticleReview

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J Schrader, M Gruwel, U Decking, C Alves. 1994. [Why do endothelial cells require adenosine triphosphate?].. https://pubmed.ncbi.nlm.nih.gov/8185718/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2022

The human mitochondrial genome contains a second light strand promoter.

The human mitochondrial genome must be replicated and expressed in a timely manner to maintain energy metabolism and supply cells with adequate levels of adenosine triphosphate. Central to this process is the idea that replication primers and gene products both arise via transcription from a single light strand promoter (LSP) such that primer formation can influence gene expression, with no consensus as to how this is regulated. Here, we report the discovery of a second light strand promoter (LSP2) in humans, with features characteristic of a bona fide mitochondrial promoter. We propose that the position of LSP2 on the mitochondrial genome allows replication and gene expression to be orchestrated from two distinct sites, which expands our long-held understanding of mitochondrial gene expression in humans.

Adenosine Triphosphate↗
PubMed2021

GCN2 kinase activation by ATP-competitive kinase inhibitors.

Small-molecule kinase inhibitors represent a major group of cancer therapeutics, but tumor responses are often incomplete. To identify pathways that modulate kinase inhibitor response, we conducted a genome-wide knockout (KO) screen in glioblastoma cells treated with the pan-ErbB inhibitor neratinib. Loss of general control nonderepressible 2 (GCN2) kinase rendered cells resistant to neratinib, whereas depletion of the GADD34 phosphatase increased neratinib sensitivity. Loss of GCN2 conferred neratinib resistance by preventing binding and activation of GCN2 by neratinib. Several other Food and Drug Administration (FDA)-approved inhibitors, such erlotinib and sunitinib, also bound and activated GCN2. Our results highlight the utility of genome-wide functional screens to uncover novel mechanisms of drug action and document the role of the integrated stress response (ISR) in modulating the response to inhibitors of oncogenic kinases.

Adenosine Triphosphate↗
PubMed2007

Protein phosphorylation corrects the folding defect of the neuroblastoma (S120G) mutant of human nucleoside diphosphate kinase A/Nm23-H1.

Human nucleoside diphosphate (NDP) kinase A is a 'house-keeping' enzyme essential for the synthesis of nonadenine nucleoside (and deoxynucleoside) 5'-triphosphate. It is involved in complex cellular regulatory functions including the control of metastatic tumour dissemination. The mutation S120G has been identified in high-grade neuroblastomas. We have shown previously that this mutant has a folding defect: the urea-denatured protein could not refold in vitro. A molten globule folding intermediate accumulated, whereas the wild-type protein folded and associated into active hexamers. In the present study, we report that autophosphorylation of the protein corrected the folding defect. The phosphorylated S120G mutant NDP kinase, either autophosphorylated with ATP as donor, or chemically prosphorylated by phosphoramidate, refolded and associated quickly with high yield. Nucleotide binding had only a small effect. ADP and the non-hydrolysable ATP analogue 5'-adenyly-limido-diphosphate did not promote refolding. ATP-promoted refolding was strongly inhibited by ADP, indicating protein dephosphorylation. Our findings explain why the mutant enzyme is produced in mammalian cells and in Escherichia coli in a soluble form and is active, despite the folding defect of the S120G mutant observed in vitro. We generated an inactive mutant kinase by replacing the essential active-site histidine residue at position 118 with an asparagine residue, which abrogates the autophosphorylation. The double mutant H118N/S120G was expressed in inclusion bodies in E. coli. Its renaturation stops at a folding intermediate and cannot be reactivated by ATP in vitro. The transfection of cells with this double mutant might be a good model to study the cellular effects of folding intermediates.

Adenosine Triphosphate↗