scholarly journals Expression cloning and functional characterization of the kidney cortex high-affinity proton-coupled peptide transporter.

1996 ◽  
Vol 93 (1) ◽  
pp. 284-289 ◽  
Author(s):  
M. Boll ◽  
M. Herget ◽  
M. Wagener ◽  
W. M. Weber ◽  
D. Markovich ◽  
...  
Keyword(s):  
Functional Characterization ◽  
Peptide Transporter ◽  
Expression Cloning ◽  
Kidney Cortex ◽  
High Affinity

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

Functional characterization of a cloned pig intestinal peptide transporter (pPepT1)

2005 ◽  
Vol 83 (1) ◽  
pp. 172-181 ◽  
Author(s):  
J. E. Klang ◽  
L. A. Burnworth ◽  
Y. X. Pan ◽  
K. E. Webb ◽  
E. A. Wong
Keyword(s):  
Functional Characterization ◽  
Peptide Transporter ◽  
Cloned Pig

scholarly journals Functional characterization of two human sulphotransferase cDNAs that encode monoamine- and phenol-sulphating forms of phenol sulphotransferase: substrate kinetics, thermal-stability and inhibitor-sensitivity studies

1994 ◽  
Vol 302 (2) ◽  
pp. 497-502 ◽  
Author(s):  
M E Veronese ◽  
W Burgess ◽  
X Zhu ◽  
M E McManus
Keyword(s):  
Thermal Stability ◽  
Human Liver ◽  
Functional Characterization ◽  
Stability Studies ◽  
Functional Relationships ◽  
High Affinity ◽  
Electrophoretic Mobilities ◽  
Sensitivity Studies ◽  
Substrate Kinetics

The present paper describes the functional characterization of two human aryl sulphotransferase (HAST) cDNAs, HAST1 and HAST3, previously isolated by us from liver and brain, respectively [Zhu, Veronese, Sansom, and McManus (1993) Biochem. Biophys. Res. Commun. 192, 671-676; Zhu, Veronese, Bernard, Sansom and McManus (1993) Biochem. Biophys. Res. Commun. 195, 120-127]. These appear to encode the two major forms of phenol sulphotransferase (PST) characterized in a number of human tissue cytosols, these being the phenolsulphating (P-PST) and monoamine-sulphating (M-PST) forms of phenol sulphotransferase. HAST1 and HAST3 cDNAs were functionally expressed in COS-7 cells and kinetically characterized using the model substrates for P-PST and M-PST, p-nitrophenol and dopamine (3,4-dihydroxyphenethylamine) respectively. COS-expressed HAST1 was shown to be enzymatically active in sulphating p-nitrophenol with high affinity (Km 0.6 microM), whereas dopamine was the preferred substrate for HAST3 (Km 9.7 microM). HAST1 could also sulphate dopamine, as could HAST3 sulphate p-nitrophenol, but the Km for these reactions were at least two orders of magnitude greater than for the preferred substrates. COS-expressed HAST1 and HAST3 displayed inhibition profiles with the ST inhibitor 2,6-dichloro-4-nitrophenol (DCNP), identical with human liver cytosolic P-PST and M-PST activities respectively. Thermal-stability studies with the expressed enzymes showed that HAST1 was considerably more thermostable (TS) than HAST3, which is consistent with P-PST being termed the TS PST and M-PST being termed the thermolabile (TL) PST. Western immunoblot analyses of the expressed PST proteins using an antibody generated to a bacterially expressed rat liver aryl/phenol ST showed that HAST1 and HAST3 migrated as single proteins with different electrophoretic mobilities (32 versus 34 kDa). This is consistent with the differences in electrophoretic mobilities observed for P-PST and M-PST in a variety of tissues reported by other workers. This report on the functional characterization of P-PST and M-PST cDNAs provides important information on the structural as well as functional relationships of human PSTs, which sulphate a vast array of exogenous and endogenous compounds.

Functional characterization of high-affinity Na+/dicarboxylate cotransporter found in Xenopus laevis kidney and heart

2005 ◽  
Vol 289 (5) ◽  
pp. C1159-C1168 ◽  
Author(s):  
Naomi Oshiro ◽  
Ana M. Pajor
Keyword(s):  
Xenopus Laevis ◽  
Cdna Sequence ◽  
Citric Acid Cycle ◽  
Functional Characterization ◽  
Activation Kinetics ◽  
Electrophysiological Properties ◽  
High Affinity ◽  
The Family ◽  
Kidney Liver

The SLC13 gene family includes sodium-coupled transporters for citric acid cycle intermediates and sulfate. The present study describes the sequence and functional characterization of a SLC13 family member from Xenopus laevis, the high-affinity Na+/dicarboxylate cotransporter xNaDC-3. The cDNA sequence of xNaDC-3 codes for a protein of 602 amino acids that is ∼70% identical to the sequences of mammalian NaDC-3 orthologs. The message for xNaDC-3 is found in the kidney, liver, intestine, and heart. The xNaDC-3 has a high affinity for substrate, including a Km for succinate of 4 μM, and it is inhibited by the NaDC-3 test substrates 2,3-dimethylsuccinate and adipate. The transport of succinate by xNaDC-3 is dependent on sodium, with sigmoidal activation kinetics, and lithium can partially substitute for sodium. As with other members of the family, xNaDC-3 is electrogenic and exhibits inward substrate-dependent currents in the presence of sodium. However, other electrophysiological properties of xNaDC-3 are unique and involve large leak currents, possibly mediated by anions, that are activated by binding of sodium or lithium to a single site.

scholarly journals Endogenous expression of the renal high-affinity H+-peptide cotransporter in LLC-PK1 cells

1998 ◽  
Vol 275 (6) ◽  
pp. C1573-C1579 ◽  
Author(s):  
Uwe Wenzel ◽  
Daniela Diehl ◽  
Martina Herget ◽  
Hannelore Daniel
Keyword(s):  
Peptide Transporter ◽  
Kidney Cortex ◽  
Proximal Tubule Cell ◽  
Ph Optimum ◽  
High Affinity ◽  
Endogenous Expression ◽  
Tubular Lumen ◽  
Lactam Antibiotic ◽  
Uptake Studies ◽  
Affinity Peptide

The reabsorption of filtered di- and tripeptides as well as certain peptide mimetics from the tubular lumen into renal epithelial cells is mediated by an H+-coupled high-affinity transport process. Here we demonstrate for the first time H+-coupled uptake of dipeptides into the renal proximal tubule cell line LLC-PK1. Transport was assessed 1) by uptake studies using the radiolabeled dipeptided-[3H]Phe-l-Ala, 2) by cellular accumulation of the fluorescent dipeptided-Ala-Lys-AMCA, and 3) by measurement of intracellular pH (pHi) changes as a consequence of H+-coupled dipeptide transport. Uptake ofd-Phe-l-Ala increased linearly over 11 days postconfluency and showed all the characteristics of the kidney cortex high-affinity peptide transporter, e.g., a pH optimum for transport ofd-Phe-l-Ala of 6.0, an apparent K m value for influx of 25.8 ± 3.6 μM, and affinities of differently charged dipeptides or the β-lactam antibiotic cefadroxil to the binding site in the range of 20–80 μM. pHi measurements established the peptide transporter to induce pronounced intracellular acidification in LLC-PK1 cells and confirm its postulated role as a cellular acid loader.

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