The mechanism of interaction between high-affinity probes and the uridine transport system of mammalian cells

1976 ◽  
Vol 89 (4) ◽  
pp. 831-838 ◽  
Author(s):  
Yael Eilam ◽  
Ioav Cabantchik
Keyword(s):  
Transport System ◽  
Mammalian Cells ◽  
High Affinity ◽  
Mechanism Of Interaction ◽  
Affinity Probes

A purine-selective nucleobase/nucleoside transporter in PK15NTD cells

2008 ◽  
Vol 294 (6) ◽  
pp. R1988-R1995 ◽  
Author(s):  
Kazi Mirajul Hoque ◽  
Linxi Chen ◽  
George P. H. Leung ◽  
Chung-Ming Tse
Keyword(s):  
Transport System ◽  
Mammalian Cells ◽  
Organic Cation ◽  
Organic Cation Transporter ◽  
Nucleoside Transport ◽  
Acidic Ph ◽  
Nucleoside Transporter ◽  
High Affinity ◽  
Naturally Occurring ◽  
Purine Analog

Nucleoside and nucleobase transporters are important for salvage of purines and pyrimidines and for transport of their analog drugs into cells. However, the pathways for nucleobase translocation in mammalian cells are not well characterized. We identified an Na-independent purine-selective nucleobase/nucleoside transport system in the nucleoside transporter-deficient PK15NTD cells. This transport system has 1,000-fold higher affinity for nucleobases than nucleosides with Kmvalues of 2.5 ± 0.7 μM for [3H]adenine, 6.4 ± 0.5 μM for [3H]guanine, 1.1 ± 0.1 mM for [3H]guanosine, and 4.2 ± 0.5 mM [3H]adenosine. The uptake of [3H]guanine (0.05 μM) was inhibited by other nucleobases and nucleobase analog drugs (at 0.5–1 mM in the order of potency): 6-mercaptopurine = thioguanine = guanine > adenine >>> thymine = fluorouracil = uracil. Cytosine and methylcytosine had no effect. Nucleoside analog drugs with modification at 2′ and/or 5 positions (all at 1 mM) were more potent than adenosine in competing the uptake of [3H]guanine: 2-chloro-2′-deoxyadenosine > 2-chloroadenosine > 2′3′-dideoxyadenosine = 2′-deoxyadenosine > 5-deoxyadenosine > adenosine. 2-Chloro-2′-deoxyadenosine and 2-chloroadenosine inhibited [3H]guanine uptake with IC50values of 68 ± 5 and 99 ± 10 μM, respectively. The nucleobase/nucleoside transporter was resistant to nitrobenzylthioinosine {6-[(4-nitrobenzyl) thiol]-9-β-d-ribofuranosylpurine}, dipyridamole, and dilazep, but was inhibited by papaverine, the organic cation transporter inhibitor decynium-22 (IC50of ∼1 μM), and by acidic pH (pH = 5.5). In conclusion, we have identified a mammalian purine-selective nucleobase/nucleoside transporter with high affinity for purine nucleobases. This transporter is potentially important for transporting naturally occurring purines and purine analog drugs into cells.

scholarly journals Identification of a novel Na+- and Cl−-coupled transport system for endogenous opioid peptides in retinal pigment epithelium and induction of the transport system by HIV-1 Tat

2003 ◽  
Vol 375 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Huankai HU ◽  
Seiji MIYAUCHI ◽  
Christy C. BRIDGES ◽  
Sylvia B. SMITH ◽  
Vadivel GANAPATHY
Keyword(s):  
Transport System ◽  
Opioid Peptides ◽  
Mammalian Cells ◽  
Retinal Pigment ◽  
Coupled Transport ◽  
Endogenous Opioid Peptides ◽  
Endogenous Opioid ◽  
Rpe Cells ◽  
High Affinity ◽  
Hiv 1

The endogenous opioid peptides enkephalins, dynorphins and endorphins consist of five or more amino acids. These peptides participate in a multitude of biological functions in mammalian cells by interacting with different subtypes of opiate receptors located on the plasma membrane and in the nucleus. Here we report on the identification of a new peptide transport system in the human retinal pigment epithelial (RPE) cells that transports a variety of endogenous opioid peptides with high affinity. We identified this novel, hitherto unrecognized, transport system when we were analysing the differential effects of Tat, the transacting factor encoded by HIV-1, on various transport processes in RPE cells. This transport system is markedly induced by Tat. This opioid transport system is energized by transmembrane Na+ and Cl− gradients and is distinct from any of the previously identified transport systems for opioid peptides in mammalian cells. Free amino acids, dipeptides, tripeptides and non-peptide opiate receptor antagonists are excluded by this newly identified transport system. The affinities of endogenous opioid peptides for this system are in the range of 0.4–40 μM. The identification of the high-affinity Na+- and Cl−-coupled transport system in mammalian cells that is specific for endogenous opioid peptides and is induced by HIV-1 Tat is of significance not only to the biology of opioid peptides but also to the pathology of HIV-1 infection in humans.

Regulation of the High-Affinity Nitrate Transport System in Wheat Roots by Exogenous Abscisic Acid and Glutamine

2007 ◽  
Vol 49 (12) ◽  
pp. 1719-1725 ◽  
Author(s):  
Chao Cai ◽  
Xue-Qiang Zhao ◽  
Yong-Guan Zhu ◽  
Bin Li ◽  
Yi-Ping Tong ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Transport System ◽  
Nitrate Transport ◽  
Wheat Roots ◽  
High Affinity

scholarly journals RCO-3 and COL-26 form an external-to-internal module that regulates the dual-affinity glucose transport system in Neurospora crassa

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jinyang Li ◽  
Qian Liu ◽  
Jingen Li ◽  
Liangcai Lin ◽  
Xiaolin Li ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Neurospora Crassa ◽  
Glucose Transport ◽  
Transport System ◽  
Rational Design ◽  
Glucose Sensor ◽  
Glucose Transporters ◽  
Glucose Fluctuation ◽  
High Affinity ◽  
Glucose Transport System

Abstract Background Low- and high-affinity glucose transport system is a conserved strategy of microorganism to cope with environmental glucose fluctuation for their growth and competitiveness. In Neurospora crassa, the dual-affinity glucose transport system consists of a low-affinity glucose transporter GLT-1 and two high-affinity glucose transporters HGT-1/HGT-2, which play diverse roles in glucose transport, carbon metabolism, and cellulase expression regulation. However, the regulation of this dual-transporter system in response to environmental glucose fluctuation is not yet clear. Results In this study, we report that a regulation module consisting of a downstream transcription factor COL-26 and an upstream non-transporting glucose sensor RCO-3 regulates the dual-affinity glucose transport system in N. crassa. COL-26 directly binds to the promoter regions of glt-1, hgt-1, and hgt-2, whereas RCO-3 is an upstream factor of the module whose deletion mutant resembles the Δcol-26 mutant phenotypically. Transcriptional profiling analysis revealed that Δcol-26 and Δrco-3 mutants had similar transcriptional profiles, and both mutants had impaired response to a glucose gradient. We also showed that the AMP-activated protein kinase (AMPK) complex is involved in regulation of the glucose transporters. AMPK is required for repression of glt-1 expression in starvation conditions by inhibiting the activity of RCO-3. Conclusions RCO-3 and COL-26 form an external-to-internal module that regulates the glucose dual-affinity transport system. Transcription factor COL-26 was identified as the key regulator. AMPK was also involved in the regulation of the dual-transporter system. Our findings provide novel insight into the molecular basis of glucose uptake and signaling in filamentous fungi, which may aid in the rational design of fungal strains for industrial purposes.

scholarly journals Functional Characterization of a High-Affinity Choline Transport System in Human Keratinocytes

2002 ◽  
Vol 119 (1) ◽  
pp. 118-121 ◽  
Author(s):  
Kathrin Hoffmann ◽  
Franziska Grafe ◽  
Wolfgang Wohlrab ◽  
Reinhard H. Neubert ◽  
Matthias Brandsch
Keyword(s):  
Transport System ◽  
Functional Characterization ◽  
Human Keratinocytes ◽  
Choline Transport ◽  
High Affinity

scholarly journals Corrigendum to: A high affinity nitrate transport system from Chlamydomonas requires two gene products (FEBS 23233)

FEBS Letters ◽  
2000 ◽  
Vol 481 (1) ◽  
pp. 88-88
Author(s):  
Jing-Jiang Zhou ◽  
Emilio Fernández ◽  
Aurora Galván ◽  
Anthony J. Miller
Keyword(s):  
Transport System ◽  
Nitrate Transport ◽  
Gene Products ◽  
High Affinity

scholarly journals High-affinity maltose/trehalose transport system in the hyperthermophilic archaeon Thermococcus litoralis.

1996 ◽  
Vol 178 (16) ◽  
pp. 4773-4777 ◽  
Author(s):  
K B Xavier ◽  
L O Martins ◽  
R Peist ◽  
M Kossmann ◽  
W Boos ◽  
...  
Keyword(s):  
Transport System ◽  
Thermococcus Litoralis ◽  
Hyperthermophilic Archaeon ◽  
High Affinity
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