Functional expression of novel peptide transporter in renal
basolateral membranes
Tomohiro
Terada,
Kyoko
Sawada,
Tatsuya
Ito,
Hideyuki
Saito,
Yukiya
Hashimoto, and
Ken-Ichi
Inui
Department of Pharmacy, Kyoto University Hospital, Faculty of
Medicine, Kyoto University, Kyoto 606 - 8507, Japan
 |
ABSTRACT |
We examined the peptide transport activity in renal
basolateral membranes. [14C]glycylsarcosine (Gly-Sar)
uptake in rat renal cortical slices was saturable and inhibited by
excess dipeptide and aminocephalosporin cefadroxil. When several renal
cell lines were screened for the basolateral peptide transport
activity, Madin-Darby canine kidney (MDCK) cells were demonstrated to
have the greatest transport activity. [14C]Gly-Sar uptake
across the basolateral membranes of MDCK cells was inhibited by di- and
tripeptide and decreased with decreases in extracellular pH from 7.4 to
5.0. The Michaelis-Menten constant value of [14C]Gly-Sar
uptake across the basolateral membranes of MDCK cells was 71 µM. The
basolateral peptide transporter in MDCK cells showed several different
[14C]Gly-Sar transport characteristics in growth
dependence, pH profile, substrate affinity, and sensitivities to
chemical modifiers from those of the apical H+-peptide
cotransporter of MDCK cells. The findings of the present investigation
indicated that the peptide transporter was expressed in the renal
basolateral membranes. In addition, from the functional characteristics, the renal basolateral peptide transporter was suggested to be distinguishable from known peptide transporters, i.e.,
H+-peptide cotransporters (PEPT1 and PEPT2) and the
intestinal basolateral peptide transporter.
kidney; Madin-Darby canine kidney cells
 |
INTRODUCTION |
THE KIDNEY PLAYS AN
IMPORTANT role in the metabolism of circulating small peptides
(1, 8). In 1977, Adibi et al. (2) reported
that the kidney possessed the greatest capacity to transport and
metabolize intravenously injected dipeptide among the tissues examined
(kidney, intestine, liver, and skeletal muscles). Subsequently, several
studies using isolated perfused kidney have demonstrated that the renal
metabolism of dipeptides mainly occurs on the luminal side, i.e.,
glomerular filtration, intraluminal hydrolysis, and luminal uptake into
the cells (7, 19, 21). However, it was also suggested that
peritubular metabolism, in addition to luminal metabolism, contributed
to the renal clearance of dipeptides, because the amount of peptide
filtrated was less than the amount of peptides that disappeared from
the perfusate (7, 19). Although the mechanisms involved in
this peritubular process were not clarified at that time, the cellular
uptake through the basolateral membranes was suggested to be involved
in this metabolism. Furthermore, Nutzenadel and Scriver
(22) reported the uptake of L-carnosine by rat
renal cortical slices. Because renal cortical slices predominantly expose the basolateral membranes to the medium (3), the
authors suggested that the uptake characteristics reflected the
transport processes through the basolateral side rather than through
the luminal side (22).
Thereafter, with respect to the investigation on the renal
handling of small peptides, numerous efforts have been devoted to
characterize the luminal transport systems using a variety of
experimental techniques. The molecular nature of these transport systems has been clarified by the identification of two kinds of
H+-peptide cotransporters, PEPT1 and PEPT2 (1, 6, 15,
18). Immunohistochemical studies revealed that PEPT1 and PEPT2
were localized at the brush-border membranes of S1 and S3 segments of
proximal tubules, respectively (25). In contrast to the
luminal peptide transport systems, there is little functional and
molecular information available on the peptide transport system
localized at the basolateral membranes in the kidney. Therefore, to
gain information about the renal basolateral peptide transporter, we examined the transport characteristics of
[14C]glycylsarcosine (Gly-Sar) in rat renal cortical
slices. In addition, to search cell lines expressing the renal
basolateral peptide transporter, three kinds of widely used renal cell
lines were screened for [14C]Gly-Sar uptake across the
basolateral membranes. As a result, Madin-Darby canine kidney (MDCK)
cells were demonstrated to show the greatest transport activity. Using
MDCK cells, we further characterized the functional properties of the
basolateral peptide transporter by comparing them with those of the
apical peptide transporter, because MDCK cells are known to express the
H+-peptide cotransporter at the apical membranes (5,
29).
 |
MATERIALS AND METHODS |
Uptake in rat renal cortical slices.
Preparation of rat renal cortical slices and uptake procedures were as
described previously (13, 17, 31). Briefly, slices weighing 50-80 mg were randomly selected and placed in oxygenized incubation buffer [(in mM) 120 NaCl, 16.2 KCl, 1 CaCl2,
1.2 MgSO4 and 10 NaH2PO4/Na2HPO4, pH
7.5)] containing [14C]Gly-Sar (1 or 5 µM) and
D-[3H]mannitol (1 or 2.5 µM).
D-[3H]mannitol was used to estimate the
extracellular trapping and nonspecific uptake of
[14C]Gly-Sar. After the incubation period, each slice was
rapidly washed twice with ice-cold incubation buffer, blotted on filter paper and solubilized in 0.5 ml of NCS II (Amersham, Buckinghamshire, UK). Then, the radioactivity was determined in 10 ml of ACS II (Amersham) by liquid scintillation counting.
Cell culture.
MDCK cells (32), LLC-PK1 cells
(24), and opossum kidney (OK) cells (14) were
cultured, as previously described. To measure the uptake of
[14C]Gly-Sar from the apical side of MDCK cells, 12-well
microplates or 35-mm plastic dishes were inoculated with 1 × 105 cells in 1 ml or with 2 × 105 cells
in 2 ml of culture medium, respectively. To measure the uptake of
[14C]Gly-Sar from the basolateral side, OK,
LLC-PK1, and MDCK cells were seeded on microporous membrane
filters (3-µm pores, 1 cm2) inside Transwell cell culture
chambers (Costar, Cambridge, MA) at a cell density of 4 × 105 cells/filter for all cells. The cell monolayers were
given culture medium every 2-3 days and were used on the 6th day
for uptake studies.
Uptake studies by monolayers.
[14C]Gly-Sar uptake by monolayers grown in 12-well
microplates and 35-mm plastic dishes was determined as described
previously (27). [14C]Gly-Sar uptake by
monolayers grown in the Transwell chambers was measured as described
previously (28).
Statistical analysis.
Each experimental point shown represents the mean ± SE of
3-12 measurements from 1-3 independent experiments. When the
error bars are not shown, they are smaller than the symbol. Data were analyzed statistically by nonpaired t-test or one-way
analysis of variance followed by Scheffé's test when multiple
comparisons were needed.
Materials.
Cefadroxil was supplied from Bristol Meyers (Tokyo, Japan).
[14C]Gly-Sar (1.78 GBq/mmol) was obtained from Daiichi
Pure Chemicals (Ibaraki, Japan).
D-[3H]mannitol (736.3 GBq/mmol) was obtained
from NEN Life Science Products (Boston, MA). Diglycine, triglycine,
tetraglycine, Gly-Sar, and p-chloromercuribenzenesulfonic
acid (PCMBS) were obtained from Sigma (St. Louis, MO).
Glycyl-L-leucine was purchased from Peptide Institute
(Osaka, Japan). Diethylpyrocarbonate (DEPC) and glycine were obtained
from Nacalai Tesque (Kyoto, Japan). All other chemicals used were of
the highest purity available.
 |
RESULTS |
Gly-Sar uptake in rat renal cortical slices.
Figure 1A shows the time
course of [14C]Gly-Sar uptake in rat renal cortical
slices. The [14C]Gly-Sar uptake was increased in a
time-dependent manner and inhibited by excess unlabeled Gly-Sar at all
times tested. The [14C]Gly-Sar uptake was not inhibited
by glycine but was significantly inhibited by Gly-Sar and cefadroxil
(Fig. 1B). The [14C]Gly-Sar uptake by rat
renal cortical slices was saturable with an apparent Michaelis-Menten
constant (Km) value of 55 µM (Fig. 1C).

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Fig. 1.
A: Time course of
[14C]glycylsarcosine (Gly-Sar) uptake in rat renal
cortical slices. Renal cortical slices were incubated at 25°C in
buffer containing 1 µM [14C]Gly-Sar in the absence
( ) or presence ( ) of 1 mM unlabeled
Gly-Sar. Each point represents the mean ± SE of 3 slices.
B: Inhibition of various compounds on
[14C]Gly-Sar uptake in rat renal cortical slices. Renal
cortical slices were incubated at 25°C in buffer containing 5 µM
[14C]Gly-Sar in the absence or presence of each inhibitor
(2 mM) for 30 min. Each column represents the mean ± SE of 3 slices. *P < 0.05, significantly different from
control. C: Concentration dependence of
[14C]Gly-Sar uptake in rat renal cortical slices. Renal
cortical slices were incubated at 25°C for 30 min in buffer
containing varying concentrations of [14C]Gly-Sar. Each
point represents the mean ± SE of 9-12 slices from 3separate
experiments.
|
|
Screening of renal cell lines for Gly-Sar uptake across the
basolateral membranes.
We screened widely used renal cell lines for the basolateral peptide
transport activity. Figure 2 shows the
time course of [14C]Gly-Sar uptake across the basolateral
membranes of OK (Fig. 2A), LLC-PK1 (Fig.
2B), and MDCK cells (Fig. 2C). The specific uptake of Gly-Sar was the greatest in MDCK cells among the cell lines
examined. [14C]Gly-Sar uptake from the apical side in
MDCK cells was also inhibited by 10 mM unlabeled Gly-Sar (Fig.
2D), indicating the expression of peptide transporter in the
apical membranes of MDCK cells. In the following experiments, we
performed a functional comparison of the apical and basolateral peptide
transporters in MDCK cells.

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Fig. 2.
Time course of [14C]Gly-Sar uptake from basolateral
side in opossum kidney (OK) (A), LLC-PK1
(B), and Madin-Darby canine kidney (MDCK) (C)
cells, and the apical side in MDCK cells (D). Each cell was
incubated with 20 µM [14C]Gly-Sar added to either the
basolateral (pH 7.4) or apical (pH 6.0) side in the absence
( ) or presence ( ) of 10 mM unlabeled
Gly-Sar. Each point represents the mean ± SE of 3 monolayers.
|
|
Functional comparison of Gly-Sar uptake by the apical and
basolateral peptide transporters in MDCK cells.
Figure 3 shows the growth dependence of
[14C]Gly-Sar uptake by the apical and basolateral peptide
transporters in MDCK cells. The [14C]Gly-Sar uptake by
both transporters was inhibited in the presence of 10 mM unlabeled
Gly-Sar throughout the duration of the culture. The specific uptake of
[14C]Gly-Sar by the apical transporter gradually
increased with the period of culture. In contrast, the specific uptake
of [14C]Gly-Sar by the basolateral peptide transporter
was increased up to the 6th day and then decreased to the 10th day. All
subsequent experiments for both transporters were done on the 6th day
after seeding to gain the greatest transport activity of the
basolateral peptide transporter.

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Fig. 3.
Growth dependence of [14C]Gly-Sar uptake
from the apical (A) and basolateral (B) sides in
MDCK cells. MDCK cells cultured for 2-10 days were incubated with
20 µM [14C]Gly-Sar (apical side, 30 min and pH 6.0;
basolateral side, 15 min and pH 7.4) in the absence ( )
or presence ( ) of 10 mM unlabeled Gly-Sar. Broken lines
show the specific [14C]Gly-Sar uptake by subtracting the
nonspecific uptake estimated in the presence of 10 mM unlabeled Gly-Sar
( ) from the total uptake ( ). Each point
represents the mean ± SE of 3 monolayers.
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|
To determine the substrate specificity, inhibition studies were carried
out. The [14C]Gly-Sar uptake by both transporters was
markedly inhibited by 10 mM diglycine and triglycine, whereas glycine
and tetraglycine at 10 mM did not show a significant inhibitory effect
on [14C]Gly-Sar uptake (Fig.
4).

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Fig. 4.
Effects of (Gly)n on
[14C]Gly-Sar uptake from the apical (A) and
basolateral (B) sides in MDCK cells. MDCK cells were
incubated at 37°C with 20 µM [14C]Gly-Sar added to
either the apical (pH 6.0, 15 min) or basolateral side (pH 7.4, 5 min)
in the absence (open bar) or presence of 10 mM inhibitors (hatched or
solid bars). Each bar represents the mean ± SE of 3 monolayers.
**P < 0.01, significantly different from control.
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Figure 5 shows the pH dependence of
[14C]Gly-Sar uptake by the apical and the basolateral
peptide transporters in MDCK cells. At all pHs examined,
[14C]Gly-Sar uptake was suppressed in the presence of
excess glycyl-L-leucine. As shown in insets of
Fig. 5, the apical peptide transporter-mediated [14C]Gly-Sar uptake was maximal at pH 6.0-6.5. In
contrast, specific uptake of [14C]Gly-Sar by the
basolateral peptide transporter was decreased in accordance with
decreases in pH from 7.4 to 5.0.

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Fig. 5.
The pH dependence of [14C]Gly-Sar uptake
from the apical (A) and basolateral (B) sides in
MDCK cells. MDCK cells were incubated for 15 min at 37°C with 20 µM
[14C]Gly-Sar, in the absence ( ) or
presence ( ) of 20 mM glycyl-L-leucine,
added to either the apical or basolateral side at various pH values.
Each point represents the mean ± SE of 3 monolayers.
Insets show the curves ( ) obtained by
subtracting the nonspecific uptake estimated in the presence of 20 mM
glycyl-L-leucine ( ) from the total uptake
( ).
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|
The [14C]Gly-Sar uptakes by the apical and the
basolateral peptide transporters in MDCK cells were both saturable. The
apparent Km values for the apical and the
basolateral peptide transporters were 440 and 71 µM, respectively
(Fig. 6).

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Fig. 6.
Concentration dependence of [14C]Gly-Sar
uptake from the apical (A) and basolateral (B)
sides in MDCK cells. MDCK cells were incubated at 37°C with varying
concentrations of [14C]Gly-Sar added to either the apical
(pH 6.0, 30 min) or basolateral side (pH 7.4, 15 min). Nonspecific
uptake was evaluated by measuring [14C]Gly-Sar uptake in
the presence of 50 mM glycyl-L-leucine, and the results are
shown after correction for the nonsaturable component. Each point
represents the mean ± SE of 6 monolayers from 2 separate
experiments.
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|
The histidine residue modifier, DEPC, and the sulfhydryl reagent,
PCMBS, were reported to show different inhibitory effects on the apical
and basolateral peptide transporters in the human intestinal cell line
Caco-2 (16, 23, 28). As shown in Fig. 7, the magnitude of inhibition produced
by DEPC was significantly greater on the apical transport rather than
on the basolateral transport, and the basolateral peptide transporter
was more sensitive to PCMBS than the apical peptide transporter.

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Fig. 7.
Effects of diethylpyrocarbonate (DEPC) (A) or
p-chloromercuribenzenesulfonic acid (PCMBS) (B)
pretreatment on [14C]Gly-Sar uptake by the apical and
basolateral peptide transporters in MDCK cells. Cells were preincubated
for 10 min with various concentrations of DEPC (pH 6.0, 25°C) or
PCMBS (pH 7.4, 4°C) on the apical (hatched bars) or basolateral
(solid bars) side. After preincubation, MDCK monolayers were rinsed
once with the incubation medium and then incubated at 37°C with 20 µM [14C]Gly-Sar added to either the apical (pH 6.0, 30 min) or basolateral side (pH 7.4, 15 min). Each bar represents the
mean ± SE of 3 to 6 monolayers from 2 separate experiments after
correction for the nonsaturable component. *P < 0.05;
**P < 0.01, significant difference between the apical
and basolateral peptide transporters.
|
|
 |
DISCUSSION |
Using human intestinal cell line Caco-2, we previously
demonstrated that the intestinal basolateral peptide transporter,
functionally distinguishable from the apical H+-peptide
cotransporter (PEPT1), was involved in the transepithelial transport of small peptides and peptidelike drugs (16, 20, 23,
28). The intestinal basolateral peptide transporter was characterized as a low-affinity and facilitative transporter (23, 28). In contrast, although it was hypothesized that the renal basolateral peptide transporter was involved in the peritubular clearance of dipeptides (7, 19), the nature of this
transporter has been little understood. Thus the purpose of the present
study was to determine whether the basolateral peptide transporter
functioned in the kidney.
Our present findings clearly demonstrated that the peptide transporter
was functionally expressed in the basolateral membranes of rat kidney
and MDCK cells. The pH profile of the renal basolateral peptide
transporter is distinct from that of the intestinal basolateral peptide
transporter. The basolateral peptide transporter in Caco-2 cells
mediated [14C]Gly-Sar uptake in an extracellular
pH-independent manner (28). Km
values of Gly-Sar for the renal basolateral peptide transporters (55 µM in rat renal cortical slices and 71 µM in MDCK cells) were much
smaller than that for the intestinal basolateral peptide transporter of
Caco-2 cells (2.1 mM) (28). These results suggested that
the renal and intestinal basolateral peptide transporters were
different from each other. The low affinity of the intestinal basolateral peptide transporter was assumed to be advantageous for the
efficient efflux of substrates into the blood (28), whereas, although speculative, the high affinity of the renal basolateral peptide transporter may contribute to the uptake of small
peptides from the circulation.
[14C]Gly-Sar uptake by the basolateral peptide
transporter in MDCK cells was inhibited by di- and tripeptide but not
by amino acid and tetrapeptide. This substrate specificity is quite
similar to that of the apical H+-peptide cotransporter in
MDCK cells. However, both transporters in MDCK cells had different
transport characteristics as follows: 1) the transport
activity of the basolateral transporter was highly dependent on the
culture duration, but that of the apical H+-peptide
cotransporter was not so much; 2) pH profiles of
[14C]Gly-Sar uptake by both transporters were quite
different from each other; 3) the basolateral transporter
showed higher affinity for [14C]Gly-Sar uptake than the
apical H+-peptide cotransporter; and 4) the
basolateral transporter was more sensitive to PCMBS than the apical
H+-peptide cotransporter, whereas the apical
H+-peptide cotransporter was more potently inhibited by
DEPC compared with the basolateral transporter. These results indicated
that the basolateral peptide transporter in MDCK cells was distinct from the apical H+-peptide cotransporter in MDCK cells.
Functional characteristics of renal basolateral transporter described
above such as pH profiles of Gly-Sar uptake appeared to be different
from PEPT1 and PEPT2 (26-28). The apparent
Km values of Gly-Sar for the renal basolateral
peptide transporter and PEPT2 were similar, but no immunostaining was
observed in the basolateral membranes of the renal tubular cells when
using anti-PEPT2 antibody (25). It is, therefore,
suggested that the renal basolateral peptide transporter was different
from PEPT1 and PEPT2. Taking all information into consideration, the
renal basolateral peptide transporter may be the novel peptide
transporter that is functionally different from PEPT1, PEPT2, and the
intestinal basolateral peptide transporter.
The renal cell lines LLC-PK1 and OK represent the basic
characteristics of proximal tubules, and MDCK displays those of distal tubules or collecting ducts (10). Of these cell lines,
MDCK cells had the greatest transport activity of
[14C]Gly-Sar through the basolateral membranes, whereas
OK cells had none, and LLC-PK1 cells had negligible
[14C]Gly-Sar transport activity under the present culture
conditions. However, using an in vitro microperfusion technique,
Barfuss et al. (4) demonstrated the transepithelial
transport of Gly-Sar in the isolated proximal straight tubules of the
rabbit kidney. Therefore, the basolateral peptide transporter would be
expressed in the proximal tubular cells. The low basolateral transport
activity in OK and LLC-PK1 cells may be due to the culture
conditions. It was reported that the expression of apical
H+-peptide cotransporter (PEPT2) in LLC-PK1
cells was dependent on culture conditions (33).
Two types of glucose transporters exist in mammals:
Na+-glucose cotransporters (SGLT1 and SGLT2) and
facilitated glucose transporters (GLUT-1 through GLUT-5). Whereas SGLTs
are primarily expressed in the brush-border membranes of intestinal and
renal epithelial cells, GLUTs are found in plasma (basolateral)
membranes of all cells examined so far (9, 11). In
addition, it is suggested that the different GLUTs expressions along
the nephron segments play unique functional roles for each isoform in
renal glucose handling; i.e., GLUTs in the proximal tubular cells
contribute to the net transepithelial reabsorption of glucose, whereas
GLUTs in the other segments may be important in cell glucose metabolism by accumulating the glucose (9, 12, 30). Similar to GLUTs, it is possible that the basolateral-type peptide transporters are
expressed in various tissues and show more functional and molecular diversity.
In conclusion, this is the first demonstration that the peptide
transporter is functionally expressed in the basolateral membranes of
the kidney. Functional characteristics of this transporter are
different from those of known peptide transporters (PEPT1, PEPT2, and
the intestinal basolateral peptide transporter). Although further studies are needed to elucidate the physiological roles of this
transporter, these findings may provide important information to
understand the renal handling of small peptides.
 |
ACKNOWLEDGEMENTS |
This work was supported in part by a Grant-in-Aid for Scientific
Research (B) and a Grant-in-Aid for Scientific Research on Priority
Areas (No. 296) from the Ministry of Education, Science, Sports, and
Culture of Japan.
 |
FOOTNOTES |
Address for reprint requests and other correspondence: K. Inui,
Kyoto Univ. Hospital, Dept. of Pharmacy, Sakyo-ku, Kyoto 606-8507, Japan (E-mail: inui{at}kuhp.kyoto-u.ac.jp).
The costs of publication of this
article were defrayed in part by the
payment of page charges. The article
must therefore be hereby marked
"advertisement"
in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Received 28 March 2000; accepted in final form 22 June 2000.
 |
REFERENCES |
1.
Adibi, SA.
Renal assimilation of oligopeptides: physiological mechanisms and metabolic importance.
Am J Physiol Renal Physiol
272:
F723-F736,
1997.
2.
Adibi, SA,
Krzysik BA,
and
Drash AL.
Metabolism of intravenously administered dipeptides in rats: effects of amino acid pools, glucose concentration and insulin glucagon secretion.
Clin Sci Mol Med
52:
193-204,
1977[ISI][Medline].
3.
Arthus, MF,
Bergeron M,
and
Scriver CR.
Topology of membrane exposure in the renal cortex slice studies of glutathione and maltose cleavage.
Biochim Biophys Acta
692:
371-376,
1982[ISI][Medline].
4.
Barfuss, DW,
Ganapathy V,
and
Leibach FH.
Evidence for active dipeptide transport in isolated proximal straight tubules.
Am J Physiol Renal Fluid Electrolyte Physiol
255:
F177-F181,
1988[Abstract/Free Full Text].
5.
Brandsch, M,
Ganapathy V,
and
Leibach FH.
H+-peptide cotransport in Madin-Darby canine kidney cells: expression and calmodulin-dependent regulation.
Am J Physiol Renal Fluid Electrolyte Physiol
268:
F391-F397,
1995[Abstract/Free Full Text].
6.
Daniel, H,
and
Herget M.
Cellular and molecular mechanisms of renal peptide transport.
Am J Physiol Renal Physiol
273:
F1-F8,
1997[Abstract/Free Full Text].
7.
Fonteles, MC,
Ganapathy V,
Pashley DH,
and
Leibach FH.
Dipeptide metabolism in the isolated perfused rat kidney.
Life Sci
33:
431-436,
1983[ISI][Medline].
8.
Ganapathy, V,
and
Leibach FH.
Carrier-mediated reabsorption of small peptides in renal proximal tubule.
Am J Physiol Renal Fluid Electrolyte Physiol
251:
F945-F953,
1986[ISI][Medline].
9.
Gould, GW,
and
Holman GD.
The glucose transporter family: structure, function and tissue-specific expression.
Biochem J
295:
329-341,
1993[ISI][Medline].
10.
Handler, JS.
Studies of kidney cells in culture.
Kidney Int
30:
208-215,
1986[ISI][Medline].
11.
Hediger, MA,
and
Rhoads DB.
Molecular physiology of sodium-glucose cotransporters.
Physiol Rev
74:
993-1026,
1994[Free Full Text].
12.
Heilig, C,
Zaloga C,
Lee M,
Zhao X,
Riser B,
Brosius F,
and
Cortes P.
Immunogold localization of high-affinity glucose transporter isoforms in normal rat kidney.
Lab Invest
73:
674-684,
1995[ISI][Medline].
13.
Hori, R,
Ishikawa Y,
Takano M,
Okano T,
Kitazawa S,
and
Inui K.
The interaction of cephalosporin antibiotics with renal cortex of rats: accumulation to cortical slices and binding to purified plasma membranes.
Biochem Pharmacol
31:
2267-2272,
1982[ISI][Medline].
14.
Hori, R,
Okamura M,
Takayama A,
Hirozane K,
and
Takano M.
Transport organic anion in the OK kidney epithelial cell line.
Am J Physiol Renal Fluid Electrolyte Physiol
264:
F975-F980,
1993[Abstract/Free Full Text].
15.
Inui, K,
and
Terada T.
Dipeptide transporters.
In: Membrane Transporters as Drug Targets, edited by Amidon GL,
and Sadée W.. New York: Kluwer Academic / Plenum, 1999, p. 269-288.
16.
Inui, K,
Yamamoto M,
and
Saito H.
Transepithelial transport of oral cephalosporins by monolayers of intestinal epithelial cell line Caco-2: Specific transport systems in apical and basolateral membranes.
J Pharmacol Exp Ther
261:
195-201,
1992[Abstract].
17.
Ito, T,
Yano I,
Masuda S,
Hashimoto Y,
and
Inui K.
Distribution characteristics of levofloxacin and grepafloxacin in rat kidney.
Pharm Res
16:
534-539,
1999[ISI][Medline].
18.
Leibach, FH,
and
Ganapathy V.
Peptide transporters in the intestine and the kidney.
Annu Rev Nutr
16:
99-119,
1996[ISI][Medline].
19.
Lowry, M,
Hall DE,
and
Brosnan JT.
Metabolism of glycine- and hydroxyproline-containing peptides by the isolated perfused rat kidney.
Biochem J
229:
545-549,
1985[ISI][Medline].
20.
Matsumoto, S,
Saito H,
and
Inui K.
Transcellular transport of oral cephalosporins in human intestinal epithelial cells, Caco-2: Interaction with dipeptide transport systems in apical and basolateral membranes.
J Pharmacol Exp Ther
270:
498-504,
1994[Abstract].
21.
Minami, H,
Daniel H,
Morse EL,
and
Adibi SA.
Oligopeptides: mechanism of renal clearance depends on molecular structure.
Am J Physiol Renal Fluid Electrolyte Physiol
263:
F109-F115,
1992[Abstract/Free Full Text].
22.
Nutzenadel, W,
and
Scriver CR.
Uptake and metabolism of
-alanine and L-carnosine by rat tissues in vitro: role in nutrition.
Am J Physiol
230:
643-651,
1976[ISI][Medline].
23.
Saito, H,
and
Inui K.
Dipeptide transporters in apical and basolateral membranes of the human intestinal cell line Caco-2.
Am J Physiol Gastrointest Liver Physiol
265:
G289-G294,
1993[Abstract/Free Full Text].
24.
Saito, H,
Yamamoto M,
Inui K,
and
Hori R.
Transcellular transport of organic cation across monolayers of kidney epithelial cell line LLC-PK1.
Am J Physiol Cell Physiol
262:
C59-C66,
1992[Abstract/Free Full Text].
25.
Shen, H,
Smith DE,
Yang T,
Huang YG,
Schnermann JB,
and
Brosius FC, III.
Localization of PEPT1 and PEPT2 proton-coupled oligopeptide transporter mRNA and protein in rat kidney.
Am J Physiol Renal Physiol
276:
F658-F665,
1999[Abstract/Free Full Text].
26.
Terada, T,
Saito H,
and
Inui K.
Interaction of
-lactam antibiotics with histidine residue of rat H+/peptide cotransporters, PEPT1 and PEPT2.
J Biol Chem
273:
5582-5585,
1998[Abstract/Free Full Text].
27.
Terada, T,
Saito H,
Mukai M,
and
Inui K.
Recognition of
-lactam antibiotics by rat peptide transporters, PEPT1 and PEPT2, in LLC-PK1 cells.
Am J Physiol Renal Physiol
273:
F706-F711,
1997[Abstract/Free Full Text].
28.
Terada, T,
Sawada K,
Saito H,
Hashimoto Y,
and
Inui K.
Functional characteristics of basolateral peptide transporter in the human intestinal cell line Caco-2.
Am J Physiol Gastrointest Liver Physiol
276:
G1435-G1441,
1999[Abstract/Free Full Text].
29.
Thamotharan, M,
and
Adibi SA.
Glycylglutamine uptake by a renal cell line: mechanism and metabolic regulation (Abstract).
FASEB J
10:
A82,
1996.
30.
Thorens, B,
Lodish HF,
and
Brown D.
Differential localization of two glucose transporter isoforms in rat kidney.
Am J Physiol Cell Physiol
259:
C286-C294,
1990[Medline].
31.
Urakami, Y,
Nakamura N,
Takahashi K,
Okuda M,
Saito H,
Hashimoto Y,
and
Inui K.
Gender differences in expression of organic cation transporter OCT2 in rat kidney.
FEBS Lett
461:
339-342,
1999[ISI][Medline].
32.
Urakami, Y,
Okuda M,
Masuda S,
Saito H,
and
Inui K.
Functional characteristics and membrane localization of rat multispecific organic cation transporters, OCT1 and OCT2, mediating tubular secretion of cationic drugs.
J Pharmacol Exp Ther
287:
800-805,
1998[Abstract/Free Full Text].
33.
Wenzel, U,
Diehl D,
Herget M,
and
Daniel H.
Endogenous expression of the renal high-affinity H+-peptide cotransporter in LLC-PK1 cells.
Am J Physiol Cell Physiol
275:
C1573-C1579,
1998[Abstract/Free Full Text].
Am J Physiol Renal Fluid Electrolyte Physiol 279(5):F851-F857
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