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Koepsell H. Methodological aspects of purification and reconstitution of transport proteins from mammalian plasma membranes. Rev Physiol Biochem Pharmacol 2006; 104:65-137. [PMID: 2940665 DOI: 10.1007/bfb0031013] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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2
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Montgomery JM, Augostini P, Stewart GL. Glucose uptake and metabolism in the Trichinella spiralis nurse cell. Int J Parasitol 2003; 33:401-12. [PMID: 12705933 DOI: 10.1016/s0020-7519(03)00013-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Isolated Trichinella spiralis nurse cells transport a significantly greater amount of glucose/mg of protein than the normal skeletal muscle cell line (L6). V(max) and K(m) estimations revealed that nurse cells have a much higher saturation point than L6 cells for glucose. The effects of numerous physiological conditions (Na(+) concentration, pH, and temperature) on nurse cell glucose uptake were investigated. It was determined that sodium concentration had no effect on glucose uptake. Low (<6.5) and high (>7.3) pH and low (5 degrees C) temperatures significantly effected glucose uptake. The two hormones, insulin and epinephrine, appeared to have little, if any, influence on the rate of glucose uptake by nurse cells. Glucose uptake was inhibited in the presence of 6-carbon carbohydrates. The H(+)/glucose symport inhibitors, dicyclohexylcarbodiimide (DCCD) and Carbonyl cyanide 4-trifluoromethoxyphenlhydrazone (FCCP), and the facilitated diffusion inhibitor phloretin also inhibited glucose uptake. Oubain, a Na(+)/glucose symport inhibitor, did not inhibit glucose uptake. These data, in conjunction with Western blot analyses, revealed that the transport of glucose occurs via H(+)/glucose symport and facilitated diffusion, perhaps through the glucose transport proteins GLUT 1 and/or 4. It was also demonstrated that nurse cells are capable of synthesising glycogen. It appears that glycogen is in a constant state of flux and physiological conditions, such as glucose concentration, significantly influence the synthesis of this macromolecule. We conclude that these results are consistent with the hypothesis that nurse cells, at least maintained in vitro, are metabolically highly active but show significant divergence from normal muscle cells in several fundamental aspects of sugar metabolism.
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Affiliation(s)
- Joel M Montgomery
- Department of Biology, University of Texas at Arlington, 76019, USA.
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3
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Hahn T, Barth S, Weiss U, Mosgoeller W, Desoye G. Sustained hyperglycemia in vitro down-regulates the GLUT1 glucose transport system of cultured human term placental trophoblast: a mechanism to protect fetal development? FASEB J 1998; 12:1221-31. [PMID: 9737725 DOI: 10.1096/fasebj.12.12.1221] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The trophoblast of human placenta is directly exposed to the maternal circulation. It forms the main barrier to maternal-fetal glucose transport. The present study investigated the effect of sustained hyperglycemia in vitro on the glucose transport system of these cells. Trophoblasts isolated from term placentas and immunopurified were cultured for 24, 48, and 96 h in DMEM containing either 5.5 (normoglycemia) or 25 mmol/l D-glucose (hyperglycemia), respectively. Initial uptake of glucose was measured using 3-O-[14C]methyl-D-glucose. Kinetic parameters were calculated as K(M) = 73 mmol/l and Vmax = 29 fmol s(-1) per trophoblast cell. Uptake rates of cells cultured under hyperglycemic conditions did not differ at exogenous D-glucose concentrations in the physiological range (1, 5.5, 10, and 15 mmol/l), but were significantly decreased by 25% (P<0.05) at diabetes-like concentrations (20 and 25 mmol/l) as compared to normoglycemic conditions. This effect was due to a decrease in Vmax (-50%), whereas K(M) remained virtually unaffected. GLUT1 mRNA levels were lower by 50% (P<0.05; Northern blotting) and GLUT1 protein was reduced by 16% (P<0.05; Western blotting) in trophoblast cells cultured under hyperglycemic vs. normoglycemic conditions. We conclude that prolonged hyperglycemia in vitro reduces trophoblast glucose uptake at substrate concentrations corresponding to blood levels of poorly controlled diabetic gravidas. This effect is due to diminished GLUT1 mRNA and protein expression in the trophoblast.
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Affiliation(s)
- T Hahn
- Department of Obstetrics and Gynecology, University of Graz Medical School, Austria.
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4
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Abstract
It is not known if the diabetes-related reduction in blood-brain barrier (BBB) transport of glucose is due to a change in the functional capacity of transporters or to an as yet unidentified mechanism occurring at the plasma membrane or cytoplasm. To increase our understanding of this problem, the cerebral blood flow, the brain uptake index (BUI) of 3-O-methyl glucose and the concentration of 3H-cytochalasin B binding sites were determined in diabetic rats and diabetic rats treated with insulin. The BUI of 3-O-methyl glucose was significantly reduced (less than 0.001) in diabetic rats (32.7 +/- 1.2%) compared to control rats (41.9 +/- 1.0%). This change could not be attributed to an alteration in cerebral blood flow or to a non-specific change in BBB permeability. Normalization of blood glucose with insulin therapy corrected the BUI measurements in diabetic rats (42.2 +/- 1.4%). The level of measurable glucose transporters measured with 3H-cytochalasin B binding assay did not appear to be reduced in the diabetic brain microvessels. The data indicate that the reduced brain uptake of glucose in chronic hyperglycemia can occur in the absence of a change in glucose transporter concentration.
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5
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Dermietzel R, Krause D. Molecular anatomy of the blood-brain barrier as defined by immunocytochemistry. INTERNATIONAL REVIEW OF CYTOLOGY 1991; 127:57-109. [PMID: 1880006 DOI: 10.1016/s0074-7696(08)60692-0] [Citation(s) in RCA: 186] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This review outlines the recent developments and improvements of our knowledge concerning the molecular composition of the BBB as revealed by immunocytochemistry. Data have been accumulated which show that the BBB exhibits a specific collection of structural and metabolic properties which are also found in tight transporting epithelia. This conclusion is substantiated by (i) the implementation of antibodies which recognize proteins of non-BBB origin, to show that these biochemical markers and the functions that they represent are localized in the BBB endothelium; and (ii) the characterization of target molecules to which polyclonal or monoclonal antibodies which have been generated to epitopes of the BBB endothelium or brain homogenates. According to these data the protein assemblies comprising the phenotypical appearance of the BBB can therefore be defined by the particular selection as well as topological expression of common epithelial antigens, rather than the expression of BBB-unique molecular species. In this respect the immunocytochemical data corroborate the physiological assumption that the BBB possesses the character of a specific polarized epithelium. Attention is also given to the description of developmental expression of BBB-related immunomarkers. By collecting the data from different sources we introduce a classification of the BBB marker proteins according to their developmental appearance. Three groups of proteins are classified with respect to their sequential expression around the time of BBB closure: Phase E (early) markers which appear before BBB closure, phase I (intermediate) markers which are expressed at the time of BBB tightening, and phase L (late) markers which are detectable after the closure of the BBB. Such a scheme may to be useful in better defining the maturation process of BBB, which apparently is not a momentary event in brain development, but rather consists of a temporally sequenced process of hierarchically structured gene expression which finally define the molecular properties of the BBB. This process continues even after parturition, especially with regard to the achievement of immunological properties of the mature BBB. By examining the developmental spatio-temporal expression of different BBB markers we conclude that the mechanisms governing the pattern of BBB maturation are not limited to the interactions occurring between glial and endothelial cells. We therefore suggest a heuristic model in a triangular interrelationship that includes differentiation effects of neurons on glia and of glia cells on the BBB endothelium.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- R Dermietzel
- Department of Anatomy and Morphology, University of Regensburg, Federal Republic of Germany
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6
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Bilan PJ, Klip A. Glycation of the human erythrocyte glucose transporter in vitro and its functional consequences. Biochem J 1990; 268:661-7. [PMID: 2363703 PMCID: PMC1131490 DOI: 10.1042/bj2680661] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Glycation of human erythrocyte membrane proteins was induced by incubation in vitro with high concentrations (80 mM or 200 mM) of D-glucose for 3 or 6 days. The extent of glycation was quantified from the covalent incorporation of 3H by reduction of the glucose glycation products with NaB3H4. For membranes incubated for 3 days with 80 mM-D-glucose, glycation in vitro of Band 4.5 (containing the glucose transporter) was equivalent to 0.11 mol of glucose/mol of glucose transporter, compared with 3H labelling in 3-day-incubated control membranes of 0.055 mol of glucose/mol of glucose transporter. In membranes incubated for 6 days with 200 mM-D-glucose, glycation increased to 0.21 mol of glucose/mol of glucose transporter, whereas the controls without glucose had 0.11 mol of glucose/mol of glucose transporter. Glycation in vitro was accompanied by a fall in the Bmax of binding of [3H]cytochalasin B (a competitive inhibitor of glucose transport), without any change in the binding affinity. The data suggest that glycated glucose transporters have decreased ability to bind cytochalasin B. It is proposed that glycation can alter glucose transporter activity.
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Affiliation(s)
- P J Bilan
- Division of Cell Biology, Hospital for Sick Children, Toronto, Ontario, Canada
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7
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Bramwell ME, Davies A, Baldwin SA. Heterogeneity of the glucose transporter in malignant and suppressed hybrid cells. Exp Cell Res 1990; 188:97-104. [PMID: 2139419 DOI: 10.1016/0014-4827(90)90282-f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Previous work has demonstrated unequivocally that the kinetics of glucose transport of tumorigenic and suppressed hybrid cells show a consistent difference. This lies in an increased affinity for glucose in the tumorigenic cell lines (i.e., a reduced Km). Evidence has also been presented that the degree of glycosylation of the transporter may affect the Km. When a suitable antiserum to the transporter present in these cells became available, it was of interest to examine the patterns of binding to immunoblots of extracts of the hybrid cell pairs. It became apparent that there was a clear difference between the two parental cell lines and that this difference was reflected in the hybrid cells. Both the tumorigenic parent and the tumorigenic hybrid cell presented a much more heterogeneous distribution of apparent molecular weights than the nontumorigenic parent or suppressed cell line. That this was probably due to differences in glycosylation was indicated by the effect of tunicamycin on the cells; this gave rise to a more homogeneous band of lower molecular weight. The significance of these differences is discussed in relation to results obtained with other tumorigenic cell lines and to the published structure of the human erythrocyte glucose transporter.
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Affiliation(s)
- M E Bramwell
- Cancer Research Campaign Cell Biology Unit, Sir William Dunn School of Pathology, University of Oxford, United Kingdom
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8
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Bagley PR, Tucker SP, Nolan C, Lindsay JG, Davies A, Baldwin SA, Cremer JE, Cunningham VJ. Anatomical mapping of glucose transporter protein and pyruvate dehydrogenase in rat brain: an immunogold study. Brain Res 1989; 499:214-24. [PMID: 2804676 DOI: 10.1016/0006-8993(89)90769-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The regional and cellular distributions of glucose transporter protein (GT) and pyruvate dehydrogenase (PDH) have been studied with an enhanced immunogold method. The results showed significant amounts of GT in neuropil within regions known to exhibit high demands for glucose whilst neuronal perikarya showed little immunostaining. In contrast PDH immunostaining was most intense in neuronal perikarya. The distributions of these proteins were compared and discussed in relation to existing data on local cerebral glucose utilization and the distribution of other important metabolic enzymes. The results suggest that glucose is transported and metabolised in neuropil and that metabolic products such as pyruvate are transported into the neuronal cell body to undergo further metabolism.
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Affiliation(s)
- P R Bagley
- MRC Toxicology Unit, Medical Research Council Laboratories, Carshalton, Surrey, U.K
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9
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Olefsky JM, Garvey WT, Henry RR, Brillon D, Matthaei S, Freidenberg GR. Cellular mechanisms of insulin resistance in non-insulin-dependent (type II) diabetes. Am J Med 1988; 85:86-105. [PMID: 3057897 DOI: 10.1016/0002-9343(88)90401-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Recent studies have led to an enhanced understanding of cellular alterations that may play an important role in the pathophysiology of non-insulin-dependent diabetes mellitus (NIDDM). The insulin receptor links insulin binding at the cell surface to intracellular activation of insulin's effects. This transducer function involves the tyrosine kinase property of the beta-subunit of the receptor. It was found that adipocytes from subjects with NIDDM had a 50 to 80 percent reduction in insulin-stimulated receptor kinase activity compared with their non-diabetic counterparts. This defect was relatively specific for the diabetic state since no decrease was observed in insulin-resistant non-diabetic obese subjects. The reduction in kinase activity was accounted for by changes in the ratio of two pools of receptors, both of which bind insulin but only one of which is capable of tyrosine autophosphorylation and subsequent kinase activation; 43 percent of the receptors from non-diabetic subjects were capable of autophosphorylation compared with only 14 percent in the NIDDM group. A major component of cellular insulin resistance in NIDDM involves the glucose transport system. Exposure of cells to insulin normally results in enhanced glucose transport mediated by translocation of glucose transporters from a low-density microsomal intracellular pool to the plasma membrane. It was found that cells from NIDDM subjects had a marked depletion of glucose transporters in both plasma membranes and low-density microsomes, relative to obese non-diabetic control participants. Obese non-diabetic persons had a normal number of plasma membrane transporters but a reduced number of low-density microsome transporters in the basal state compared with lean control volunteers; insulin induced the translocation of relatively fewer transporters from the low-density microsome to the plasma membrane in the obese subgroups. In addition to the diminished number of glucose transporters, cells from both NIDDM and obese subjects had impaired functional activity of glucose carriers since decreased whole-cell glucose transport rates could not be entirely explained by the magnitude of the decrement in the number of plasma membrane transporters. Thus, impaired glucose transport is due to both a numerical and functional defect in glucose transporters. The cellular content of high-density microsomal transporters was the same in lean and obese control volunteers and NIDDM subjects, suggesting that transporter synthesis is normal and that cellular depletion results from increased protein turnover once transporters leave the high-density microsomal subfraction.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- J M Olefsky
- Department of Medicine, University of California, San Diego 92161
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10
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Langdon RG, Holman VP. Immunological evidence that band 3 is the major glucose transporter of the human erythrocyte membrane. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 945:23-32. [PMID: 3179308 DOI: 10.1016/0005-2736(88)90358-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have previously reported that human erythrocyte band 3 contains 90-95% of the reconstitutable glucose transport activity of the erythrocyte membrane (Shelton, R.L. and Langdon, R.G. (1983) Biochim. Biophys. Acta 733, 25-33). We have now found that monoclonal and polyclonal antibodies to epitopes on band 3 specifically removed band 3 and more than 90% of the reconstitutable glucose transport activity from unfractionated octylglucoside extracts of erythrocyte membranes; nonimmune serum removed neither. Western blots of whole membrane extracts revealed that the polyclonal antibody to band 4.5 used to isolate cDNA clones presumed to code for the transporter (Mueckler, M., Caruso, C., Baldwin, C.A., Pancio, M., Blench, J., Morris, H.B., Allard, W.J., Lienhard, G.E. and Lodish, H.F. (1985) Science 229, 941-945) reacts strongly with six discrete bands in the 4.5 region. A monoclonal antibody to band 3 also reacts with a Mr 55,000 component of band 4.5. We conclude that band 3 contains the major glucose transporter of human erythrocytes, and that the transport activity in band 4.5 might be attributable to a band 3 fragment. Band 3 is probably a multifunctional transport protein responsible for transport of glucose, anions, and water.
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Affiliation(s)
- R G Langdon
- University of Virginia School of Medicine, Department of Biochemistry, Charlottesville 22908
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11
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Haspel HC, Rosenfeld MG, Rosen OM. Characterization of antisera to a synthetic carboxyl-terminal peptide of the glucose transporter protein. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)57406-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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12
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Flier JS, Mueckler MM, Usher P, Lodish HF. Elevated levels of glucose transport and transporter messenger RNA are induced by ras or src oncogenes. Science 1987; 235:1492-5. [PMID: 3103217 DOI: 10.1126/science.3103217] [Citation(s) in RCA: 573] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
An accelerated rate of glucose transport is among the most characteristic biochemical markers of cellular transformation. To study the molecular mechanism by which transporter activity is altered, cultured rodent fibroblasts transfected with activated myc, ras, or src oncogenes were used. In myc-transfected cells, the rate of 2-deoxy-D-glucose uptake was unchanged. However, in cells transfected with activated ras and src oncogenes, the rate of glucose uptake was markedly increased. The increased transport rate in ras- and src-transfected cells was paralleled by a marked increase in the amount of glucose transporter protein, as assessed by immunoblots, as well as by a markedly increased abundance of glucose transporter messenger RNA. Exposure of control cells to the tumor-promoting phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) for 18 hours had a similar effect of increasing the rate of glucose transport and the abundance of transporter messenger RNA. For ras, src, and TPA, the predominant mechanism responsible for activation of the transport system is increased expression of the structural gene encoding the glucose transport protein.
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13
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May J. Labeling of human erythrocyte band 3 with maltosylisothiocyanate. Interaction with the anion transporter. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61481-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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14
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Matthaei S, Garvey WT, Horuk R, Hueckstaedt TP, Olefsky JM. Human adipocyte glucose transport system. Biochemical and functional heterogeneity of hexose carriers. J Clin Invest 1987; 79:703-9. [PMID: 3102556 PMCID: PMC424180 DOI: 10.1172/jci112874] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We have investigated glucose transport proteins in isolated human adipocytes. Using the cytochalasin B binding assay to measure glucose transporters in subcellular membrane subfractions, we found that insulin induced translocation of intracellular glucose transporters to the cell surface. Isoelectric focusing of glucose transporters photolabeled with [3H]cytochalasin B revealed two distinct glucose transporter isoforms in low density microsomes focusing at pH 5.6 and pH 6.4, but only the pH 5.6 isoform was detectable in plasma membranes and only the pH 6.4 form was found in the high density microsomes. Insulin recruited only the pH 5.6 glucose transporter from the low density microsomes to the plasma membrane with no effect on the pH 6.4 transporter isoform. The results suggest that the pH 6.4 species is an immature form of the glucose transporter initially located in the high-density microsome fraction, which then migrates to the low-density microsomes where it matures (converted to pH 5.6 species) and becomes available for insulin-mediated recruitment to the plasma membrane.
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15
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Rampal AL, Jung EK, Chin JJ, Deziel MR, Pinkofsky HB, Jung CY. Further characterization and chemical purity assessment of the human erythrocyte glucose transporter preparation. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 859:135-42. [PMID: 3730374 DOI: 10.1016/0005-2736(86)90208-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Chemical and functional purity of the human erythrocyte glucose transporter preparation obtained by DEAE column chromatography after octyl glucoside solubilization was assessed. The cytochalasin B binding capacity of the preparation indicates that the preparation is 60-85% functional glucose transporter. Gel filtration chromatography on TSK 250 column separates this preparation into at least three major peptide fractions, namely, P0, P1 and P2, with apparent Mr of approx. 80 000, 43 000 and 17 000, respectively. When the preparation is photolabelled with [3H]cytochalasin B prior to the separation only P0 and P1 are labelled. Exposure of the preparation to octyl glucoside or to ultraviolet light irradiation results in an increase in P0 in a time-dependent manner with a concomitant and proportional reduction in P1, without affecting P2 appreciably. For individual preparations, relative abundance of P0 and P1 vary widely in a reciprocal fashion, while that of P2 is practically fixed at approx. 10% of the total protein. The specific activity of cytochalasin B binding of each preparation correlates linearly with the relative abundance of P1 of the preparation, which gives a calculated specific binding activity of 22 nmol/mg protein for this fraction. These results indicate that P1 and P0 are native and denatured transporter, respectively, while P2 is contaminating protein impurities. These results demonstrate that the glucose transporter preparation contains approx. 10% of nontransporter protein impurities, with a varying amount (up to 30%) of denatured transporter, and that the transporter free of the chemical impurities and the denatured transporter can be obtained by a gel filtration chromatography of this preparation.
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16
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Abbott RE, Schachter D, Batt ER, Flamm M. Sulfhydryl substituents of the human erythrocyte hexose transport mechanism. THE AMERICAN JOURNAL OF PHYSIOLOGY 1986; 250:C853-60. [PMID: 3717328 DOI: 10.1152/ajpcell.1986.250.6.c853] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Sulfhydryl substituents of the hexose transport mechanism of human erythrocyte membranes were studied with membrane-impermeant and -permeant maleimide derivatives. Three sulfhydryl classes have been identified on the basis of their reactivity toward the reagents and their effects on the transport mechanism. Type I sulfhydryl is located at the outer (exofacial) surface of the membrane and bound covalently on treatment of intact cells with the membrane-impermeant glutathione-maleimide. This sulfhydryl is required for the transport, and it is protected from alkylation, i.e., its reactivity toward maleimides is decreased by the presence of D-glucose or cytochalasin B. Type II sulfhydryl is also required for the transport, but it differs from type I in that D-glucose (but not cytochalasin B) increases the reactivity toward maleimides. Further, it is located at the endofacial surface of the membrane, since reaction with glutathione-maleimide occurs only in leaky ghosts and not in intact cells. Alkylation by glutathione-maleimide of type I and type II sulfhydryls increases the half-saturation for the binding of D-glucose to erythrocyte membranes. In contrast, inactivation of type III sulfhydryls by N-ethylmaleimide or dipyridyl disulfide decreases the half-saturation concentration for the binding of D-glucose and other transported hexoses to the membranes; nontransported sugars are not affected similarly. Type III sulfhydryl is not inactivated by the polar reagent glutathione-maleimide and is probably located in a nonpolar domain of the transport mechanism. Inactivation of either type I or II sulfhydryls decreases or eliminates the flux asymmetry of the hexose transport mechanism.
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Kasahara M, Inui K, Takano M, Hori R. Distinction of three types of D-glucose transport systems in animal cells. Biochem Biophys Res Commun 1985; 132:490-6. [PMID: 4062937 DOI: 10.1016/0006-291x(85)91160-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Immunoblotting of plasma membrane fractions from rat kidney cortex with antibody to human erythrocyte glucose transporter showed a single major cross-reacting material of 48K in basolateral membrane fractions possessing a facilitated diffusion system for D-glucose, but not in brush border membrane fractions which have a Na-dependent active transport system. Cytochalasin B inhibited D-glucose uptake in basolateral membrane vesicles but not in brush border vesicles. Cross-reacting materials of 44-55K were detected in several animal cells exhibiting facilitated diffusion systems, including a hormone dependent system. These results indicate molecular difference between glucose transporters of facilitated diffusion systems and active transport systems.
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18
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Deziel MR, Jung CY, Rothstein A. The topology of the major band 4.5 protein component of the human erythrocyte membrane: characterization of reactive cysteine residues. BIOCHIMICA ET BIOPHYSICA ACTA 1985; 819:83-92. [PMID: 4041454 DOI: 10.1016/0005-2736(85)90198-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A preparation of band 4.5 protein of the red cell membrane, containing largely the sugar transporter, was labelled with the sulfhydryl reagent N-ethyl [14C]maleimide. In preparations denatured with sodium dodecyl sulfate (SDS), all five sulfhydryl groups present in the peptide, Mr 45 000 to 60 000, react with the alkylating agent within 20 min at 37 degrees C. If the peptide is reconstituted in lipid vesicles and cleaved with trypsin before extraction and denaturation with SDS, three sulfhydryl groups are found in a 30 kDa fragment and two in a 19 kDa fragment. In 'native' reconstituted protein only three groups react, even after two hours of exposure, two in the 30 kDa fragment and one in the 19 kDa fragment. Thus, one sulfhydryl group is cryptic, inaccessible to N-ethylmaleimide in each fragment. In intact cells, the single reactive group of the 19 kDa fragment can be protected against reaction with N-ethylmaleimide by the impermeant sulfhydryl reagent, p-chloromercuribenzene sulfonate (PCMBS). It is, therefore, considered to be exposed on the outer face of the membrane. The two reactive groups of the 30 kDa fragment are not protected by PCMBS and are, therefore, not considered to be exposed to the outside medium. Cytochalasin B, a competitive inhibitor of sugar transport affords temporary protection of the exofacial group of the 19 kDa against reaction with N-ethylmaleimide, and affords longer term protection of one of the reactive groups of the 30 kDa fragment. These findings allow conclusions about the topology of the sugar transport protein in the bilayer. Both proteolytic fragments must cross the bilayer. One of three reactive sulfhydryl groups is exofacial and two may be cytoplasmic. The two cryptic groups may be located within the bilayer.
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19
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Allard WJ, Lienhard GE. Monoclonal antibodies to the glucose transporter from human erythrocytes. Identification of the transporter as a Mr = 55,000 protein. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39399-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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20
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Haspel HC, Birnbaum MJ, Wilk EW, Rosen OM. Biosynthetic precursors and in vitro translation products of the glucose transporter of human hepatocarcinoma cells, human fibroblasts, and murine preadipocytes. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39596-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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21
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22
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Etemadi AH. Functional and orientational features of protein molecules in reconstituted lipid membranes. ADVANCES IN LIPID RESEARCH 1985; 21:281-428. [PMID: 3161297 DOI: 10.1016/b978-0-12-024921-3.50014-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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23
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Deziel MR, Rothstein A. Proteolytic cleavages of cytochalasin B binding components of Band 4.5 proteins of the human red blood cell membrane. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 1984; 776:10-20. [PMID: 6541055 DOI: 10.1016/0005-2736(84)90245-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The putative hexose transport component of Band 4.5 protein of the human erythrocyte membrane was covalently photolabelled with [3H]cytochalasin B. Its transmembrane topology was investigated by electrophoretically monitoring the effect of proteinases applied to intact erythrocytes, unsealed ghosts, and a reconstituted system. Band 4.5 was resistant to proteolytic digestion at the extracellular face of the membrane in intact cells at both high and low ionic strengths. Proteolysis at the cytoplasmic face of the membrane in ghosts or reconstituted vesicles resulted in cleavage of the transporter into two membrane-bound fragments, a peptide of about 30 kDa that contained its carbohydrate moiety, and a 20 000 kDa nonglycosylated peptide that bore the cytochalasin B label. Because it is produced by a cleavage at the cytoplasmic face and because the carbohydrate moiety is known to be exposed to the outside, the larger fragment must cross the bilayer. It has been reported that the Band 4.5 sugar transporter may be derived from Band 3 peptides by endogenous proteolysis, but the cleavage pattern found in the present study differs markedly from that previously reported for Band 3. Minimization of endogenous proteolysis by use of fresh cells, proteinase inhibitors, immediate use of ghosts and omission of the alkaline wash resulted in no change in the incorporation of [3H]cytochalasin B into Band 4.5, and no labelling of Band 3 polypeptides. These results suggest that the cytochalasin B binding component of Band 4.5 is not the product of proteolytic degradation of a Band 3 component.
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24
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Lienhard GE, Crabb JH, Ransome KJ. Endoglycosidase f cleaves the oligosaccharides from the glucose transporter of the human erythrocyte. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 769:404-10. [PMID: 6421318 DOI: 10.1016/0005-2736(84)90324-9] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The glucose transporter from human erythrocytes is a heterogeneously glycosylated protein that runs as a very broad band of average apparent Mr 55 000 upon sodium dodecyl sulfate polyacrylamide gel electrophoresis. When the purified preparation of transporter, solubilized in Triton X-100, was treated with endoglycosidase F, much of it ran as a sharp band of Mr 46 000 upon electrophoresis. Moreover, endoglycosidase F released 80% of the radioactivity in a preparation of the transporter labeled in its oligosaccharides with galactose oxidase and tritiated borohydride, and almost none of the remaining radioactivity was located in the Mr 46 000 band. These results suggest that endoglycosidase F can release virtually all of the carbohydrate linked to the transporter polypeptide. A quantitative analysis of the gels was complicated by partial aggregation of polypeptides that occurs due to prolonged incubation in Triton X-100, but at least 65% of the protein in the preparation of purified transporter is the 46 kDa polypeptide. The extracellular domain of the transporter is very resistant to proteolysis; no cleavage occurred upon treatment of intact erythrocytes with seven different proteases at high concentration.
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25
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Identification of the erythrocyte nucleoside transporter as a band 4.5 polypeptide. Photoaffinity labeling studies using nitrobenzylthioinosine. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(17)43981-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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26
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Klip A, Walker D, Ransome KJ, Schroer DW, Lienhard GE. Identification of the glucose transporter in rat skeletal muscle. Arch Biochem Biophys 1983; 226:198-205. [PMID: 6685458 DOI: 10.1016/0003-9861(83)90285-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The glucose transporter in the plasma membrane of rat skeletal muscle has been identified by two approaches. In one, the transporter was detected as the polypeptide that was differentially labeled by photolysis with [3H]cytochalasin B in the presence of L- and D-glucose. [3H]Cytochalasin B is a high-affinity ligand for the transporter that is displaced by D-glucose. In the other, the transporter was detected by means of its reaction with rabbit antibodies against the purified glucose transporter from human erythrocytes. By both procedures, the transporter was found to be a polypeptide with a mobility corresponding to a molecular weight of 45,000-50,000 upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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27
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Ingermann RL, Bissonnette JM, Koch PL. D-Glucose-sensitive and -insensitive cytochalasin B binding proteins from microvillous plasma membranes of human placenta. Identification of the D-glucose transporter. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 730:57-63. [PMID: 6681985 DOI: 10.1016/0005-2736(83)90316-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cytochalasin B was found to bind to at least two distinct sites in human placental microvillous plasma membrane vesicles, one of which is likely to be intimately associated with the glucose transporter. These sites were distinguished by the specificity of agents able to displace bound cytochalasin B. [3H]Cytochalasin B was displaceable at one site by D-glucose but not by dihydrocytochalasin B; it was displaceable from the other by dihydrocytochalasin B but not by D-glucose. Some binding which could not be displaced by D-glucose + cytochalasin B binding site. Cytochalasin B can be photoincorporated into specific binding proteins by ultraviolet irradiation. D-Glucose specifically prevented such photoaffinity labeling of a microvillous protein component(s) of Mr = 60,000 +/- 2000 as determined by urea-sodium dodecyl sulfate acrylamide gel electrophoresis. This D-glucose-sensitive cytochalasin B binding site of the placenta is likely to be either the glucose transporter or be intimately associated with it. The molecular weight of the placental glucose transporter agrees well with the most widely accepted molecular weight for the human erythrocyte glucose transporter. Dihydrocytochalasin B prevented the photoincorporation of [3H]cytochalasin B into a polypeptide(s) of Mr = 53,000 +/- 2000. This component is probably not associated with placental glucose transport. This report presents the first identification of a sodium-independent glucose transporter from a normal human tissue other than the erythrocyte. It also presents the first molecular weight identification of a human glucose-insensitive high-affinity cytochalasin B binding protein.
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28
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Klip A, Walker D. The glucose transport system of muscle plasma membranes: characterization by means of [3H]cytochalasin B binding. Arch Biochem Biophys 1983; 221:175-87. [PMID: 6681949 DOI: 10.1016/0003-9861(83)90134-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
A membrane-rich preparation was isolated from adult rat skeletal muscle in low salt media and further fractionated in sucrose gradients. Fraction F2, with a relative density of 1.092-1.119, consisted of sealed membrane vesicles which were enriched in plasma membrane markers. These vesicles were capable of stereospecific D-glucose uptake which was sensitive to cytochalasin B (CB). The membranes were also enriched in high affinity [3H]CB binding activity (Kd of 0.28 microM). [3H]CB binding to the glucose carrier of these plasma membranes, estimated as the fraction of binding protectable by D-glucose, ranged between 2.5 and 7.4 pmol/mg protein in several membrane preparations. The amount of [3H]CB binding to muscle membranes from newborn and adult rats was not markedly different. Trypsin, at low concentrations, altered the molecular weight of several membrane components, without affecting [3H]CB binding. Higher concentrations of trypsin abolished [3H]CB binding. Both 2,4-dinitrofluorobenzene (0.1 mM) and N-ethylmaleimide (15 mM) inhibited [3H]CB binding; inhibition by these reagents was prevented by inclusion of micromolar concentrations of CB in the reaction mixture. Several procedures that extracted specific proteins enriched the D-glucose-sensitive [3H]CB binding to the protein-depleted membranes. Antibody raised against the glucose carrier of human red cell membranes cross-reacted with a polypeptide of Mr about 45K of muscle membranes which might represent the glucose carrier.
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29
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Photoaffinity labeling of the human erythrocyte nucleoside transporter by N6-(p-Azidobenzyl)adenosine and nitrobenzylthioinosine. Evidence that the transporter is a band 4.5 polypeptide. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32908-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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30
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Sase S, Takata K, Hirano H, Kasahara M. Characterization and identification of the glucose transporter of human erythrocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 693:253-61. [PMID: 6185146 DOI: 10.1016/0005-2736(82)90493-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The glucose transporter was purified from human erythrocytes (Kasahara, M. and Hinkle, P.C. (1977) J. Biol. Chem. 252, 7384-7390). The following results support the conclusion that a major protein in the purified transporter fraction, zone 4.5 is the glucose transporter (or a part of the transporter) and is different from band 3: (1) peptide maps of zone 4.5 were similar throughout the broad band in sodium dodecyl sulfate-gel electrophoresis and were different from those of band 3, (2) specific binding of cytochalasin B was found to the transporter fraction, but not to a band 3 fraction, (3) the N-terminal amino acid analysis of the transporter fraction showed a single N-terminal of lysine, whereas the band 3 fraction showed no clear N-terminal, and (4) the rabbit antibody raised against the transporter fraction formed a precipitation line with the transporter fraction, but not with the band 3 fraction. A filtration apparatus was devised for quick and accurate measurement of cytochalasin B binding, with which results comparable to those from equilibrium dialysis were obtained.
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31
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32
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McCall AL, Millington WR, Wurtman RJ. Metabolic fuel and amino acid transport into the brain in experimental diabetes mellitus. Proc Natl Acad Sci U S A 1982; 79:5406-10. [PMID: 6752947 PMCID: PMC346906 DOI: 10.1073/pnas.79.17.5406] [Citation(s) in RCA: 113] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We used the Oldendorf brain uptake index method to study the blood-brain barrier transport of several metabolic substrates in diabetes. Glucose transport into the brain was decreased by 1/3 in rats with moderate diabetes induced by prior injection of streptozotocin (65 mg/kg of body weight). The transports of mannose and the poorly metabolized hexoses 2-deoxyglucose and 3-O-methylglucose were similarly reduced. Likewise, brain glucose transport was decreased in rats with alloxan-induced diabetes. These alterations in brain hexose influx appeared to be related to chronic (1-2 days) hyperglycemia rather than to insulin-lack per se. Thus, starvation of the diabetic rats for 48 hr restored both the plasma glucose concentration and brain hexose transport to normal. Conversely, the substitution of 10% sucrose for their drinking water both increased plasma glucose and decreased hexose transport in insulin-treated diabetic rats. The 45% decrease in maximal glucose transport rate observed and the uniformity of diminished hexose transport probably imply a decrease in the number of available high-affinity transport carriers at the blood-brain barrier. This defect was specific for hexoses in that the transports of neutral and basic amino acids and of beta-hydroxybutyrate were not similarly affected. These results suggest that chronic hyperglycemia decreases the number of hexose carrier molecules available at the blood-brain barrier. Such an adaptation could operate to decrease the net flux of glucose into the brain during sustained hyperglycemia. It also may explain the abnormal sensitivity to abrupt blood glucose lowering in patients with diabetes mellitus.
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33
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Nickson JK, Jones MN. The reconstitution of the human erythrocyte sugar transporter in planar bilayer membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 690:31-40. [PMID: 6751392 DOI: 10.1016/0005-2736(82)90235-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The degradation of human erythrocyte membrane proteins in relation to the identification of the monosaccharide transporter has been investigated in whole membrane preparations and membrane protein extracts by polyacrylamide gel electrophoresis in sodium n-dodecyl sulphate and iodine-125 labelling. Evidence is presented for the degradation of band 3 polypeptide to lower molecular weight material some of which appears in region 4.5 of the polyacrylamide gel electrophoresis profile. It is found that the degradation process is inhibited by phenylmethylsulphonyl fluoride and is only significant in membrane extracts in the absence of detergent (Triton X-100) and on prolonged incubation at 37 degrees C, conditions which do not prevail during the isolation of membrane protein extracts for reconstitution studies. Extracts of band 3 and band 4.5 have been prepared and reconstituted in bilayer lipid membranes. The permeabilities of the reconstituted systems to D-glucose have been investigated and it is found that only bilayers incorporating band 4.5 exhibited enhanced monosaccharide transport. A linear relationship between D-glucose transport and the concentration of protein in the aqueous phase bathing the bilayers suggests a partitioning of the protein into the bilayer. Reconstitution is stereospecific and inhibited by cytochalasin B.
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34
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Baldwin SA, Baldwin JM, Lienhard GE. Monosaccharide transporter of the human erythrocyte. Characterization of an improved preparation. Biochemistry 1982; 21:3836-42. [PMID: 6890381 DOI: 10.1021/bi00259a018] [Citation(s) in RCA: 176] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The human erythrocyte monosaccharide transporter has been purified through the use of the dialyzable detergent octyl glucoside. It was found that the transporter denatures in the detergent and that the rate of this process could be reduced by increasing the ratio of phospholipid to detergent. The transporter was obtained in higher yield and with a higher specific activity for cytochalasin B binding than has been previously reported. Scatchard plot analysis of cytochalasin B binding to the reconstituted preparations gave a dissociation constant of 1.5 X 10(-7) M, and there were found to be 15.3 nmol of sites/mg of protein. On the basis of a value of 46 000 for the molecular weight of the polypeptide, this specific activity corresponds to 0.70 site/polypeptide chain; and there are reasons to believe that the value of the stoichiometry may be one site per functional transporter polypeptide. The complete amino acid composition and the N- and C-terminal residues of the transporter have been determined. Both the intact transporter and transporter that had been partially depleted of carbohydrate by treatment with endo-beta-galactosidase were found to migrate anomalously upon sodium dodecyl sulfate--polyacrylamide gel electrophoresis, relative to the behavior of standard proteins.
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35
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Cytochalasin B. A natural photoaffinity ligand for labeling the human erythrocyte glucose transporter. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34372-2] [Citation(s) in RCA: 78] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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36
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Carter-Su C, Pessin JE, Mora R, Gitomer W, Czech MP. Photoaffinity labeling of the human erythrocyte D-glucose transporter. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(19)83793-6] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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37
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Lienhard GE, Kim HH, Ransome KJ, Gorga JC. Immunological identification of an insulin-responsive glucose transporter. Biochem Biophys Res Commun 1982; 105:1150-6. [PMID: 7046752 DOI: 10.1016/0006-291x(82)91090-7] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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38
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Wheeler TJ, Simpson IA, Sogin DC, Hinkle PC, Cushman SW. Detection of the rat adipose cell glucose transporter with antibody against the human red cell glucose transporter. Biochem Biophys Res Commun 1982; 105:89-95. [PMID: 7046746 DOI: 10.1016/s0006-291x(82)80014-4] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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39
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Salter DW, Baldwin SA, Lienhard GE, Weber MJ. Proteins antigenically related to the human erythrocyte glucose transporter in normal and Rous sarcoma virus-transformed chicken embryo fibroblasts. Proc Natl Acad Sci U S A 1982; 79:1540-4. [PMID: 6280190 PMCID: PMC346010 DOI: 10.1073/pnas.79.5.1540] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Antibody raised against the purified human erythrocyte glucose transporter specifically precipitated four proteins from normal and Rous sarcoma virus-transformed chicken embryo cells: a major protein of Mr 41,000 and minor proteins of Mr 68,000, 73,000, and 82,000. The Mr 41,000 and 82,000 proteins were found only in a membrane fraction, not in the soluble fraction, and displayed a heterogeneous mobility on NaDodSO4/polyacrylamide gel electrophoresis, suggesting glycosylation. The Mr 41,000 and 82,000 proteins were increased in amount after malignant transformation in direct proportion to the increase in hexose transport rate, and the increase was dependent on the expression of the src gene product, as revealed with a temperature-conditional src mutant. We suggest that the Mr 41,000 and 82,000 proteins are the glucose transporter of chicken embryo fibroblasts, or a component of the glucose transporter. These experiments provide direct evidence that malignant transformation increases the rate of glucose transport by increasing the number of transporters in the membrane.
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40
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Jarvis SM, Young JD. Nucleoside translocation in sheep reticulocytes and fetal erythrocytes: a proposed model for the nucleoside transporter. J Physiol 1982; 324:47-66. [PMID: 6284922 PMCID: PMC1250693 DOI: 10.1113/jphysiol.1982.sp014100] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
1. Nucleoside transport by fetal erythrocytes from nucleoside-permeable and nucleoside-impermeable type new-born lambs and by reticulocytes from adult sheep was compared with that of mature erythrocytes from adult sheep of the two phenotypes.2. Fetal cells and reticulocytes transported [U-(14)C]uridine rapidly, with little difference between cells from the two types of sheep. Transport occurred by a saturable uptake mechanism with similar properties to that present in mature cells from adult nucleoside-permeable type animals, except for an approximately 100-fold higher V(max).3. This increased translocation capacity was associated with increased numbers of high-affinity [(3)H]nitrobenzylthioinosine binding sites ( approximately 2000-3000 sites/cell compared with approximately 20 sites/cell for mature nucleoside-permeable sheep erythrocytes).4. The calculated transport capacity for each nucleoside translocation site is therefore similar in all cell types (140-180 molecules/site. s at 25 degrees C, assuming that each transport site binds a single molecule of inhibitor). These values compare favourably with turnover estimates for the nucleoside transporter from human and pig erythrocytes.5. Loss of nucleoside transport activity after birth closely paralleled loss of [(3)H]nitrobenzylthioinosine binding sites and the progressive loss of fetal cells from the circulation. Similarly, reticulocyte maturation in vitro was also associated with rapid loss of both nucleoside transport capacity and inhibitor binding activity.6. p-Chloromercuriphenylsulphonate and trypsin had no effect on [(3)H]nitrobenzylthioinosine binding to intact fetal cells. In contrast, both agents markedly inhibited binding to isolated ;ghosts' where both sides of the cell membrane were accessible to reagent. p-Chloromercuriphenylsulphonate inhibition was markedly reduced in the presence of uridine, and reversed by addition of dithiothreitol.7. We conclude that nucleoside transport changes during ontogeny and reticulocyte maturation in the sheep as well as species differences in nucleoside transport capacity are regulated by variations in the numbers of functional transport sites per cell rather than by changes in the activity of a constant number of sites. It is also likely that the nucleoside carrier exhibits chemical asymmetry.8. A simple molecular model of the erythrocyte nucleoside transporter consistent with these and other known properties of the carrier is proposed.
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41
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Fannin FF, Evans JO, Gibbs EM, Diedrich DF. Phloretinyl-3'-benzylazide: a high affinity probe for the sugar transporter in human erythrocytes. I. Hexose transport inhibition and photolabeling of mutarotase. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 649:189-201. [PMID: 7198487 DOI: 10.1016/0005-2736(81)90406-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A new phloretin derivative, phloretinyl-3'-benzylazide (PBAz), has been synthesized and compared with phloretin for its ability to inhibit the hexose transporter in human erythrocyte membranes in subdued light. Transport measurements were made using the light scattering (Orskov optical) method and a Millipore filtration technique with isotopically labeled sugars. Initial rates of sugar flux were measured under four different conditions to test for inhibition asymmetry. In each experimental condition, PBAz is from 6-20-times more potent than phloretin, making it one of the most effective reversible inhibitors known. Although both agents penetrate the cell membrane, they apparently fail to reach inhibitory levels at the inner surface over the time course of our nonequilibrated experiments, because of extensive binding to hemoglobin. The mechanism by which PBAz and its parent phloretin inhibit transport is pure competition with hexose for the carrier which faces the exterior of the membrane. If given time to equilibrate with the cells, the inhibition by both agents converts to a mixed type, i.e., both competitive and noncompetitive. The noncompetitive component could be due to inhibition of those transporter units oriented internally. Alternatively pre-equilibration with the inhibitors may cause them to attain high levels in the lipid membrane and produce nonspecific effects. PBAz and its precursor amine, phloretinyl-3'-benzylamine (PBA), compete with glucose for the sugar binding site on mutarotase at least as well as phloretin. When exposed to long wavelength ultraviolet radiation, PBAz is converted to a reactive intermediate which becomes covalently bound to the enzyme. Both irreversible ligand attachment and mutarotase inhibition are related to dose of the azide and irradiation time, but inactivation is from 5 to 6-times greater than label incorporation. We conclude that PBAz is a potentially useful photoaffinity labeling agent capable of covalently interacting with the transporter site facing the exterior of the red cell.
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42
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43
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Fröman G, Lundhal P, Acevedo F. Partial purification of the D-glucose transport protein from human erythrocyte membranes by affinity chromatography on wheat germ lectin-Sepharose. FEBS Lett 1981; 129:100-4. [PMID: 6895070 DOI: 10.1016/0014-5793(81)80765-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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44
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Jones MN, Nickson JK. Monosaccharide transport proteins of the human erythrocyte membrane. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 650:1-20. [PMID: 7196262 DOI: 10.1016/0304-4157(81)90006-x] [Citation(s) in RCA: 100] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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45
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Lundahl P, Acevedo F, Fröman G, Phutrakul S. The stereospecific D-glucose transport activity of cholate extracts from human erythrocyte membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 644:101-7. [PMID: 7196260 DOI: 10.1016/0005-2736(81)90064-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The glucose transport protein of human erythrocyte membranes was solubilized with cholate to facilitate rapid reconstitution and direct glucose transport measurements. This may simplify the isolation of the native glucose transporter. In most experiments the membranes were prepared from fresh blood within 8 h, frozen in liquid nitrogen and stored at -70 degrees C to minimize proteolytic degradation. Solubilization with 25 mM cholate in the presence of 200 mM NaCl at pH 8.4 for 12 min at room temperature gave a high D-glucose transport activity. The solubilized mixture contained 20% of the total membrane protein, only 6% of the polypeptides of molecular weight around 90000, 23% of the polypeptides of molecular weight around 55000, 30% of the phospholipids and at least 6% of the stereospecific D-glucose transport activity. At cholate concentrations up to 22 mM the ratio of solubilized phospholipids to cholate increased steeply, concomitant with an increase in solubilized activity. Above 30 mM cholate the activity diminished. At 4 degrees C the activity of the extract decreased rapidly within the first day and slowly during the next few days. The initial changes seem to have produced a fairly stable, but not native form or fragment of the transporter. When 20 mM EDTA and 5 mM dithioerythritol were included in the solubilization mixture a high activity was preserved for about one day.
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46
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Baldwin J, Gorga J, Lienhard G. The monosaccharide transporter of the human erythrocyte. Transport activity upon reconstitution. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)69509-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Jarvis SM, Young JD. Extraction and partial purification of the nucleoside-transport system from human erythrocytes based on the assay of nitrobenzylthioinosine-binding activity. Biochem J 1981; 194:331-9. [PMID: 7305987 PMCID: PMC1162748 DOI: 10.1042/bj1940331] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Nitrobenzylthioinosine, a potent nucleoside-transport inhibitor, binds to high-affinity sites on the human erythrocyte membrane. This binding is a specific interaction with functional nucleoside-transport sites. The protein(s) responsible for high-affinity nitrobenzylthioinosine binding was purified 13-fold by treatment of haemoglobin-free 'ghosts' with EDTA (pH 11.2) to remove extrinsic proteins, extraction of the protein-depleted membranes with Triton X-100 and passage of the soluble extract through a DEAE-cellulose column equilibrated with Triton X-100. Void-volume fractions were collected and treated with Bio-Beads SM-2 to remove detergent. These fractions contained 31% of the starting nitrobenzylthioinosine-binding activity. They also contained D-glucose-sensitive cytochalasin B-binding activity. Nitrobenzylthioinosine binding to the partially purified preparation was saturable (apparent Kd 1.6 nM) and inhibited by nitrobenzylthioguanosine, dipyridamole and uridine. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of pooled void-volume fractions revealed the presence of only two detectable protein bands, the broad zone 4.5 (containing glucose-transport protein) and a small amount of band 7.
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