Endocrinology Vol. 139, No. 3 827-831
Copyright © 1998 by The Endocrine Society
Characterization of GLUT5 Domains Responsible for Fructose Transport1
A. E. Buchs,
S. Sasson,
H. G. Joost and
E. Cerasi
Department of Endocrinology and Metabolism, Hebrew University
Hadassah Medical Center (A.E.B., E.C.), and the Department of
Pharmacology, Hebrew University Hadassah Medical School and School of
Pharmacy (S.S.), Jerusalem, Israel; and Institut für
Pharmakologie und Toxikologie, Rheinisch-Westfälische Technische
Hochschule Aachen (H.G.J.), Aachen, Germany
Address all correspondence and requests for reprints to: Dr. A. E. Buchs, Department of Endocrinology and Metabolism, Hadassah University Hospital, Jerusalem 91120, Israel. E-mail: buchs{at}hadassah.org.il
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Abstract
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The domains responsible for the fructose specificity of GLUT5 were
investigated by creating chimeras of GLUT5 with the selective glucose
transporter GLUT3, which were expressed in Xenopus
oocytes. 3-O-Methylglucose uptake of chimeric GLUT3–5
(M11; GLUT3 to the 11th transmembrane domain, GLUT5 to the carboxyl
end) was similar to that of GLUT3, while fructose was not transported.
Fructose uptake of chimeric GLUT5–3 (M3–5) to -5 (GLUT3 from the 3rd
to 5th transmembrane domains, the rest GLUT5) was similar to that of
GLUT5; no glucose was transported. Four chimeras transported neither
fructose nor glucose: GLUT3–5 (M5; GLUT3 to the 5th transmembrane
domain, GLUT5 to the carboxyl end), GLUT5–3 (M2; GLUT5 to the 2nd
transmembrane domain, the rest GLUT3), GLUT5–3 (M3–11) to -5 (GLUT3
between the 3rd and 11th transmembrane domains, the rest GLUT5) and
GLUT5–3 (M3–5) to -5–3 (M11; GLUT3 from the 3rd to 5th transmembrane
domains and after the 11th transmembrane domain, the rest GLUT5). They,
nevertheless, induced full-size proteins that were transported to the
cell surface, as demonstrated by exofacial labeling with biotin. To
conclude, the GLUT5 domain from the amino-terminus to the third
transmembrane domain and that between the 5th and 11th transmembrane
stretches seem to be necessary for fructose uptake.
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Introduction
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THE FACILITATED diffusion of glucose
through the plasma membrane of mammalian cells is mediated by members
of the glucose transporter (GLUT) family. Six GLUT isoforms (GLUT1
through GLUT 7, glut6 being a pseudogene) have been
characterized (1, 2, 3). They show different kinetic properties and
substrate specificity; their cell type-restricted expression is
determined by the needs of the respective tissues (4, 5). Mueckler,
based on hydropathy analysis, suggested that the GLUT protein crosses
the plasma membrane 12 times; the transmembrane stretches show highly
conserved primary amino acid sequences between the various isoforms (6, 7). This model, although widely accepted, has been challenged by
Fischbarg, who proposes that GLUTs fold as rigid ß-barrel
transportation units (8).
The structure/function relationship of GLUTs has attracted considerable
interest. By introducing single amino acid mutations (mainly into
GLUT1) it has been shown that transmembrane stretches M7 to M9 are
important for binding of the exofacial ligand ATB-BMPA, whereas
cytochalasin B binding involves transmembrane stretches M10 and M11
(9, 10, 11). However, single amino acid changes are difficult to interpret,
because transport activity may be unspecifically modified due to
changes in the tertiary structure of GLUT. More conclusive data on the
function-specific domains of GLUT may be obtained by constructing
chimera between isoforms with different affinities for glucose
(e.g. between GLUT4 and GLUT2) or with different substrate
specificities (e.g. GLUT3 and GLUT5) (11, 12, 13).
We have taken advantage of the marked substrate selectivities of GLUT3
(glucose transport) and GLUT5 (fructose transport), and created
chimeric transporters containing various combinations of GLUT3 and
GLUT5 domains to identify the sequences that ascribe specific function
to these transporters. We found two protein domains of GLUT5 to be
responsible for fructose uptake (amino-terminus to first intracellular
loop, and the sequence between the 5th and 11th transmembrane
stretches), whereas at least parts of the carboxyl-terminal of
GLUTs seem to be required for transport function (11, 14, 15, 16, 17, 18).
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Materials and Methods
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Xenopus laevis frogs were purchased locally (Uzi
Maler, Beer Sheba, Israel). Restriction enzymes were obtained from
Promega (Madison, WI), the T7 capping kit was purchased from Epicenter
(Madison, WI), and the TA overhang kit was obtained from Invitrogen
(San Diego, CA). 3-O-[3H]Methylglucose and
D-[U-14C]fructose were purchased from
Amersham (Aylesbury, UK); NHS-LC biotin was purchased from Pierce
Chemical Co. (Rockford, IL); streptavidin-agarose beads, benzacain, and
collagenase were obtained from Sigma Chemical Co. (St. Louis, MO).
Opti-Fluor was obtained from Packard Instruments (Meriden, CT).
Construction of GLUT5-GLUT3 chimeras
GLUT3 and GLUT5 complementary DNAs were gifts from Dr. Graeme
Bell, University of Chicago (Chicago, IL). Chimeras were created
through splicing by overlap extension with internal primers containing
15 bp each of GLUT3 and GLUT5. As an example, GLUT3–5 (M5) was created
by two subsequent PCR reactions. First, GLUT3 served as a template, the
external primer annealed at the beginning of the coding sequence, and
the internal primer annealed at 522 bp of the noncoding strand of
GLUT3. This amplified GLUT3 stretch with a GLUT5 tail was annealed to
GLUT5, and the full-length chimeric GLUT3–5 (M5) was amplified with
two external primers, one annealing at the start codon of the coding
strand of GLUT3 and the other at the stop codon of the noncoding strand
of GLUT5. The chimeric PCR product was subcloned into a TA overhang
plasmid pCRII to facilitate sequencing. The following six chimera were
created, as shown in Figs. 1
and 2. The GLUTs were then subcloned into the
oocyte expression vector pGOV, linearized with SmaI,
in vitro transcribed into capped RNA, and injected into
Xenopus laevis oocytes with a Picospritzer II microinjector
(General Valve Corp., Fairfield, NJ).
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Figure 1. Schematic representation of GLUT3/5 chimera
according to Mueckler’s hydropathy analysis. Arrows
show the sites of chimeric insertions. The first number indicates the
amino acid number of GLUT3; the second indicates that of the GLUT5
sequence.
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Figure 2. Schematic representation of the chimeric GLUTs:
GLUT 3–5 (M11): GLUT3 to amino acid 420 (11th transmembrane domain)
followed by GLUT5 from amino acid 430 to the carboxyl-end; GLUT3–5
(M5), GLUT3 to amino acid 174 (5th transmembrane domain), GLUT5 from
amino acid 183 to the carboxyl-end; GLUT5–3 (M2), GLUT5 to amino acid
101 (2nd transmembrane domain), GLUT3 from amino acid 94 to the
carboxyl-end; GLUT5–3 (M3–11)/-5, GLUT5 to amino acid 101, GLUT 3
from amino acid 94 to amino acid 420 (stretch between 3rd and 11th
transmembrane domains), GLUT5 from amino acid 430 to the carboxyl-end;
GLUT5–3 (M3–5)/-5, GLUT5 to amino acid 101, GLUT3 from amino acid 94
to amino acid 174, GLUT5 from amino acid 183 to the carboxyl-end;
GLUT5–3 (M3–5)/-5–3 (M11), GLUT5 to amino acid 101, GLUT3 from amino
acid 94 to amino acid 174, GLUT5 from amino acid 183 to amino acid 429,
GLUT3 from amino acid 421 to the carboxyl-end.
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Construction of transporters containing GLUT4 carboxyl-terminus
extension
These were constructed to permit identical Western blotting
characteristics of the chimeras with anti-GLUT 4 antibody. Wild-type
GLUTs and chimeras were amplified by PCR, omitting the stop codon. The
terminal 78 bp of GLUT4 were amplified in a separate PCR reaction. The
two resulting PCR products were ligated and subcloned into the oocyte
expression vector pGOV. We thus obtained full-length GLUTs with the
addition of the last 26 carboxyl-terminal amino acids of
GLUT4.
Oocyte preparation
Xenopus laevis frogs were anesthetized in 0.1%
benzacain, and part of the ovary was removed by laparatomy. The oocytes
were separated by digestion in 2 mg/ml collagenase-OR medium (82.5
mM NaCl, 2 mM KCl, 1.8 mM
CaCl2, 1 mM MgCl2, and 5
mM HEPES pH 7.5). Oocytes were kept in OR medium
supplemented with streptomycin-penicillin at 18 C.
Hexose uptake
Groups of 10 oocytes were incubated for 10 min in
3-O-methylglucose (1 µCi/assay) or fructose (0.2
µCi/assay) (4, 12, 14) in the presence of 1 mM unlabeled
hexose, washed in ice-cold OR medium, solubilized in scintillation
vials with Opti-Fluor, and counted in a ß-counter.
Biotinylation
Washed oocytes were incubated in NHS-LC biotin-PBS for 30 min at
4 C, then lysed in Triton buffer containing protease inhibitors. After
centrifugation, the middle layer was saved, and an aliquot was taken
(total lysate); streptavidin-agarose beads were added to the rest and
incubated for 30 min at 4 C. The suspension was centrifuged, and the
pellet was solubilized in Laemmli buffer in the presence of 150
mM dithiothreitol (membrane fraction). Proteins were
separated on 8% acrylamide gel by SDS-PAGE electrophoresis,
transferred onto nitrocellulose, and blotted with antibodies against
the GLUT4 carboxyl-terminus.
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Results
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Expression of wild-type GLUTs in oocytes
Glucose uptake of oocytes expressing GLUT3 and GLUT5 (Fig. 3, Table 1). Oocytes were injected with
increasing amounts of GLUT3 or GLUT5 RNA. Three days later,
3-O-methylglucose uptake was assessed in groups of 10
oocytes. Maximal hexose transport was noted at injection of 10 ng RNA.
Oocytes injected with RNA encoding for GLUT3 had 4.9 ± 0.9-fold
3-O-methylglucose uptake than sham-injected oocytes. In
oocytes injected with GLUT5 RNA, glucose uptake was not different from
that in sham-treated oocytes (1.08 ± 0.04-fold).
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Figure 3. Left panel,
3-O-Methylglucose uptake (see Materials and
Methods). The bars represent the mean of 14
experiments for GLUT3, five experiments for GLUT5, and three
experiments for the other constructs. Values are given as glucose
uptake of GLUT-injected oocytes divided by uptake of sham-treated
oocytes in the same experiment. *, P < 0.0002; **,
P < 0.05 (compared with GLUT5, by Mann-Whitney
test). Right panel, Fructose uptake (see
Materials and Methods). The bars
represent the mean of seven experiments for GLUT3, nine experiments for
GLUT5, and three experiments for the other constructs. Values are
ratios of fructose uptake of GLUT-injected oocytes over that of
sham-treated oocytes in the same experiment. *, P
< 0.004; **, P < 0.02 (compared with GLUT3, by
Mann-Whitney test).
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Fructose uptake of oocytes expressing GLUT3 and GLUT5 (Fig. 3
, Table 1). Injection of GLUT5 RNA led to a 2.43 ± 0.29-fold
increase in fructose uptake compared with that in sham-injected
oocytes, whereas GLUT3 RNA caused 1.36 ± 0.22-fold fructose
uptake, which was not different from that by sham-treated oocytes.
Expression of chimeric GLUTs in oocytes
Expression of chimeras with the carboxyl-terminus of GLUT5
(Fig. 3, Table 1). The chimeric GLUT3–5 (M11) induced
3-O-methylglucose uptake that was 2.45 ± 0.55-fold
that of sham-injected oocytes. In contrast, fructose uptake was not
significantly different from that of sham-treated oocytes, thus showing
glucose selectivity similar to that of wild-type GLUT3. GLUT3–5 M5
injection did not lead to significant uptake of either glucose or
fructose.
Expression of chimeras with the carboxyl-terminus of GLUT 3
(Fig. 3, Table 1). The chimera GLUT5–3 (M2) and GLUT5–3
(M3–5)/-5–3 (M11) failed to induce significant glucose or fructose
uptake.
Expression of chimeras with both the amino- and carboxyl-termini of
GLUT5 (Figs. 3 and 4, Table 1). The
injection of chimeric GLUT5–3 (M3–5)/-5 into oocytes induced a
3.04 ± 0.51-fold fructose uptake compared with that of
sham-injected oocytes, similar to that of oocytes injected with GLUT5
RNA. 3-O-Methylglucose uptake, however, was not different
from that of sham-injected oocytes. Injection of GLUT5–3 (M3–11)/-5
induced no significant glucose or fructose uptake.
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Figure 4. Expression of GLUTs and their chimera in the
plasma membrane. Groups of 20 oocytes were prepared and subjected to
biotinylation as described in Materials and Methods. In
the upper panel, GLUT5 and the nonfunctional chimera
GLUT3–5 (M5) with the carboxyl-terminus of GLUT4 were blotted
(indicated by 5 and M5, respectively). The lower panel
shows corresponding findings for GLUT3 and the nonfunctional chimeric
GLUT5–3 (M2) with the carboxyl-terminus of GLUT 4 (indicated by 5–3
and 3, respectively). Sh., Sham-injected oocytes.
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Expression of chimeric GLUTs containing the GLUT4 tail. The
carboxy-terminal 26 amino acids of GLUT4 were added to the wild-type
GLUT3 and GLUT5 as well as to the above-mentioned functionally silent
chimeras. Oocytes injected with these constructs induced glucose and
fructose uptake to the same extent as those without the GLUT4 tail
(data not shown). Chimeras that did not induce hexose transport
remained functionally silent also after the addition of the GLUT4
tail.
Cell surface expression of GLUTs
Oocytes were incubated in biotin/PBS, and membranes were separated
from total lysates with streptavidin beads. After SDS-PAGE, the GLUTs
and their chimeras were blotted with antibodies against the added GLUT4
tail. As expected, both wild-type GLUT3 and GLUT5 were present in large
amounts in the total lysate as well as at the cell surface.
Immunoblotting the chimeras GLUT5–3 (M2), GLUT5–3 (M3–5)/-5–3
(M11), GLUT5–3 (M3–11)/-5, and GLUT3–5 (M5) revealed that they
induced full-size proteins that were transported to the cell surface,
as they could be exofacially labeled by biotin (Fig. 4). Glycosylation
varied among the different chimeric proteins, as indicated on the gel
by the differences in size and appearance of the bands.
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Discussion
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GLUT3 induces glucose, but not fructose, transport; GLUT5, on the
other hand, is a pure fructose transporter. These marked differences in
substrate specificity may facilitate structure/function correlation
studies of relevance for the glucose transporter family at large. We,
therefore, created chimeras that comprised domains of GLUT3 and GLUT5
and expressed them in the oocyte model. Of 6 constructs, only 2 induced
hexose transport. The chimeric protein GLUT5–3 (M3–5)/-5, which is a
GLUT5 molecule, except that the sequence between the end of the 1st
intracellular loop and the beginning of the 3rd extracellular loop is
derived from GLUT3, induced fructose uptake with the same efficiency as
the wild-type GLUT5. The chimeric GLUT3–5 (M11), which is GLUT3 until
the end of the 11th transmembrane stretch, with the rest being GLUT5,
is as glucose selective as the wild-type GLUT3. The induction of
fructose transport by GLUT5–3 (M3–5)/-5 indicates that protein
domains between the transmembrane stretches M3 to M5 are not important
for the substrate specificity of GLUT5, nor are sequences distal to the
11th transmembrane stretch, as GLUT3–5 (M11) did not transport
fructose. Of interest in this context is the finding that the 7th
transmembrane stretch of GLUT2 is crucial for its fructose transport
ability, as recently reported by Gould (19). It may thus be suggested
that at least 2 protein domains are needed for fructose uptake: 1
between the amino-terminus and the first intracellular loop, and the
other between the 6th and 11th transmembrane stretches of GLUT5. The
last 72 amino acids of GLUT5 are apparently not responsible for its
fructose specificity. Point mutations introduced into GLUT1 in
transmembrane stretches M7, M10, and M11, but not M6, decreased the
transport activity, stressing the importance of these domains for
glucose transport (10, 20, 21). Thus, taking together all of these
results, we speculate that certain areas between M6 and M11 are of
major importance for all GLUT isoforms to sustain normal transport
function.
The other tested chimera induced a full-length protein and were
transported to the plasma membrane and exposed to the cell surface as
assessed by their ability to undergo biotinylation; nevertheless, they
failed to induce hexose transport. It is probable that the insertion of
GLUTs into the plasma membrane in a manner to permit normal function
may require more than one specific protein domain. However, the primary
sequence of the protein does not seem to contain sufficient
information. For example, we concluded that the amino-terminus of GLUT5
may be important for transport, as GLUT3–5 (M5), with the primary
amino acid sequence of GLUT3 to the transmembrane stretch M5 and
thereafter GLUT5, was functionally inactive; exchanging the
amino-terminus sequence of GLUT3 with that of GLUT5 transformed this
silent chimeric transporter [GLUT3–5 (M5)] into a functional protein
[GLUT5–3 (M3–5)/-5]. However, the chimeric GLUT5–3 (M2), which
contains an identical initial GLUT5 sequence, was nonfunctional. The
functional silence was not correlated to whether the amino- or
carboxyl-ends of the chimera were derived from GLUT3 or GLUT5. Similar
observations were made by Oka, who studied GLUT5-GLUT1 chimeras
expressed in CHO cells (12), and by Gould, who studied GLUT2-GLUT3
chimeras expressed in oocytes (12). We showed in an earlier study that
although chimeras consisting of the amino-terminus of GLUT2 and the
carboxyl-terminus of GLUT4 did not induce glucose transport, their
exact mirror constructs were functionally active (11). Based on these
results and the possibility that certain nonfunctioning chimeras fold
incorrectly, we suggest that several protein domains need to interact
with each other in a precise mode, as dictated not only by the primary
amino acid sequence but also by the yet to be defined three-dimensional
structure of the protein.
Here, we also tested whether oligomerization of GLUTs through
sulfhydryl bond creation between cysteins in transmembrane stretch M10
is necessary for hexose transport. The coinjection of GLUT3 RNA with
the nonfunctioning chimeric GLUT5–3 (M2) into oocytes did not decrease
the rate of hexose transport compared to the effect of GLUT3 expression
alone (data not shown), suggesting that heterooligomerization of the
GLUT isoforms, which should have deranged the correct configuration
necessary for normal transport, did not occur. These results together
with the fact that not all GLUT isoforms contain cysteins at the same
position and that cystein less GLUT 1 induces normal glucose
transport (22) render this hypothesis unlikely.
A major handicap in the correct interpretation of data derived from
GLUT structure/function studies is the lack of crystallographic data on
the transporter protein, which prevents modeling of the designed
chimera. Our chimeras were constructed according to Mueckler’s model,
based on hydropathy analysis (6). Care was taken to exchange protein
domains between GLUT3 and GLUT5 without interrupting transmembrane
stretches. Recently, Fischbarg and Vera suggested that the structure of
GLUT is a rigid ß-barrel containing a channel of approximately 20 Å,
with the protein crossing the cell membrane 16 times (6, 23). The
chimeric GLUT5–3 (M3–5)/-5, which transported fructose, did interrupt
transmembrane stretches if plotted according to Fischbarg’s model. The
nonfunctioning chimeric GLUT5–3 (M3–11)/-5, on the other hand, did
not interrupt the transmembrane stretches in the same model. It
appears, therefore, that none of present models have the power to
predict the functional characteristics of GLUTs. Crystallography-based
models will have to be developed to obtain a precise description of the
functionally important molecular domains of GLUT isoforms.
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Acknowledgments
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We appreciate the technical assistance of Michal Neiger-Eliash,
Ayelet Reches, and Rachel Oron.
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Footnotes
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1 This work was supported by the German-Israeli Foundation for
Scientific Research and Development (I-256–148.02/92). 
Received July 29, 1997.
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References
|
|---|
-
Mueckler M 1994 Facilitative glucose
transporters. Eur J Biochem 219:713–725[Medline]
-
James DE, Strube M, Mueckler M 1989 Molecular
cloning and characterization of an insulin-regulatable glucose
transporter. Nature 338:83–87[CrossRef][Medline]
-
Permutt MA, Koranyi L, Keller K, Lacy PE, Scharp DW,
Mueckler M 1989 Cloning and functional expression of a human
pancreatic islet glucose-transporter cDNA. Proc Natl Acad Sci USA 86:8688–8692[Abstract/Free Full Text]
-
Burant CF, Takeda J, Brot LE, Bell GI, Davidson NO 1992 Fructose transporter in human spermatozoa and small intestine is
GLUT5. J Biol Chem 267:14523–14526[Abstract/Free Full Text]
-
Bell GI, Kayano T, Buse JB, Burant CF, Takeda J, Lin D,
Fukumoto H, Seino S 1990 Molecular biology of mammalian glucose
transporters. Diabetes Care 13:198–208[Abstract]
-
Mueckler M, Caruso C, Baldwin SA, Panico M, Blench I,
Morris HR, Allard WJ, Lienhard GE, Lodish HF 1995 Sequence and
structure of a human glucose transporter. Science 229:941–945
-
Hresko RC, Kruse M, Strube M, Mueckler M 1994 Topology of the Glut 1 glucose transporter deduced from glycosylation
scanning mutagenesis. J Biol Chem 269:20482–20488[Abstract/Free Full Text]
-
Fischbarg J, Cheung M, Czegledy F, Li J, Iserovich P,
Kuang K, Hubbard J, Garner M, Rosen OM, Golde DW 1993 Evidence
that facilitative glucose transporters may fold as beta-barrels. Proc
Natl Acad Sci USA 90:11658–11662[Abstract/Free Full Text]
-
Hashiramoto M, Kadowaki T, Clark AE, Muraoka A,
Momomura K, Sakura H, Tobe K, Akanuma Y, Yazaki Y, Holman GD 1992 Site-directed mutagenesis of GLUT1 in helix 7 residue 282 results in
perturbation of exofacial ligand binding. J Biol Chem 267:17502–17507[Abstract/Free Full Text]
-
Mori H, Hashiramoto M, Clark AE, Yang J, Muraoka A,
Tamori Y, Kasuga M, Holman GD 1994 Substitution of tyrosine 293 of
GLUT1 locks the transporter into an outward facing conformation. J
Biol Chem 269:11578–11583[Abstract/Free Full Text]
-
Buchs A, Wu L, Morita H, Whitesell RR, Powers AC 1995 Two regions of GLUT 2 glucose transporter protein are responsible
for its distinctive affinity for glucose. Endocrinology 136:4224–4230[Abstract]
-
Inukai K, Katagiri H, Takata K, Asano T, Anai M,
Ishihara H, Nakazaki M, Kikuchi M, Yazaki Y, Oka Y 1995 Characterization of rat GLUT5 and functional analysis of chimeric
proteins of GLUT1 glucose transporter and GLUT5 fructose transporter.
Endocrinology 136:4850–4857[Abstract]
-
Wandel S, Buchs AE, Schuermann A, Summers S, Powers AC,
Shanahan M, Joost HG 1996 Glucose transport activity and ligand
binding (cytochalasin B, IAPS-forskolin) of chimeric constructs of
GLUT2 and GLUT4 expressed in COS-7 cells. Biochim Biophys Acta 10:1–9
-
Oka Y, Asano T, Shibasaki Y, Lin J, Tsukuda K, Katagiri
H, Akanuma Y, Takaku F 1990 C-Terminal truncated glucose
transporter is locked into an inward-facing form without transport
activity. Nature 345:550–553[CrossRef][Medline]
-
Lin J, Asano T, Katagiri H, Tsukuda K, Ishihara H,
Inukai K, Yazaki Y, Oka Y 1992 Deletion of C-terminal 12 amino
acids of GLUT1 protein does not abolish the transport activity. Biochem
Biophys Res Commun 184:865–870[CrossRef][Medline]
-
Katagiri H, Asano T, Ishihara H, Tsukuda K, Lin JL,
Inukai K, Kikuchi M, Yazaki Y, Oka Y 1992 Replacement of
intracellular C-terminal domain of GLUT1 glucose transporter with that
of GLUT2 increases Vmax and Km of transport activity. J Biol Chem 267:22550–22555[Abstract/Free Full Text]
-
Tanti JF, Gautier N, Cormont M, Baron V, Van Obberghen
E, Le Marchand Brustel Y 1992 Potential involvement of the
carboxy-terminus of the Glut 1 transporter in glucose transport.
Endocrinology 131:2319–2324[Abstract]
-
Due AD, Qu ZC, Thomas JM, Buchs A, Powers AC, May
JM 1995 Role of the C-terminal tail of the GLUT1 glucose
transporter in its expression and function in Xenopus laevis
oocytes. Biochemistry 34:5462–5471[CrossRef][Medline]
-
Arbuckle MI, Kane S, Porter LM, Seatter MJ, Gould
GW 1996 Structure-function analysis of liver-type (GLUT2) and
brain-type (GLUT3) glucose transporters: expression of chimeric
transportes in Xenopus oocytes suggests an important role
for putative transmembrane helix 7 in determining substrate
selectivity. Biochemistry 35:16519–16527[CrossRef][Medline]
-
Garcia JC, Strube M, Leingang K, Keller K, Mueckler
MM 1992 Amino acid substitutions at tryptophan 388 and tryptophan
412 of the HepG2 (Glut1) glucose transporter inhibit transport activity
and targeting to the plasma membrane in Xenopus oocytes.
J Biol Chem 267:7770–7776[Abstract/Free Full Text]
-
Wellner M, Monden I, Mueckler MM, Keller K 1995 Functional consequences of proline mutations in the putative
transmembrane segments 6 and 10 of the glucose transporter GLUT1. Eur
J Biochem 227:454–458[Medline]
-
Due AD, Cook JA, Fletcher SJ, Qu ZC, Powers AC, May
JM 1995 A "cysteineless" GLUT1 glucose transporter has normal
function when expressed in Xenopus oocytes. Biochem Biophys
Res Commun 208:590–596[CrossRef][Medline]
-
Fischbarg J, Cheung M, Li J, Iserovich P, Czegledy F,
Kuang K, Garner M 1995 Are most transporters and channels beta
barrels? Mol Cell Biochem 140:147–162
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Abstract
Introduction
