Glucose Transporter Asymmetries in the Bovine Blood-Brain Barrier
The transport of glucose across the mammalian blood-brain barrier is mediated by the GLUT1 glucose transporter, which is concentrated in the endothelial cells of the cerebral microvessels. Several studies supported an asymmetric distribution of GLUT1 protein between the luminal and abluminal membran...
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Published in | The Journal of biological chemistry Vol. 276; no. 16; pp. 12725 - 12729 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Biochemistry and Molecular Biology
20.04.2001
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Subjects | |
Online Access | Get full text |
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Summary: | The transport of glucose across the mammalian blood-brain barrier is mediated by the GLUT1 glucose transporter, which is concentrated
in the endothelial cells of the cerebral microvessels. Several studies supported an asymmetric distribution of GLUT1 protein
between the luminal and abluminal membranes (1:4) with a significant proportion of intracellular transporters. In this study
we investigated the activity and concentration of GLUT1 in isolated luminal and abluminal membrane fractions of bovine brain
endothelial cells. Glucose transport activity and glucose transporter concentration, as determined by cytochalasin B binding,
were 2-fold greater in the luminal than in the abluminal membranes. In contrast, Western blot analysis using a rabbit polyclonal
antibody raised against the C-terminal 20 amino acids of GLUT1 indicated a 1:5 luminal:abluminal distribution. Western blot
analysis with antibodies raised against either the intracellular loop of GLUT1 or the purified erythrocyte protein exhibited
luminal:abluminal ratios of 1:1. A similar ratio was observed when the luminal and abluminal fractions were exposed to the
2- N -4[ 3 H](1-azi-2,2,2,-trifluoroethyl)benzoxyl-1,3-bis-( d -mannos-4-yloxyl)-2-propylamine ([ 3 H]ATB-BMPA) photoaffinity label. These observations suggest that either an additional glucose transporter isoform is present
in the luminal membrane of the bovine blood-brain barrier or the C-terminal epitope of GLUT1 is âmaskedâ in the luminal membrane
but not in the abluminal membranes. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.M010897200 |