The glucose transporter GLUT1 catalyses facilitative diffusion of glucose into erythrocytes and is responsible for glucose supply to the brain and other organs. Dysfunctional mutations may lead to GLUT1 deficiency syndrome, whereas overexpression of GLUT1 is a prognostic indicator for cancer. Despite decades of investigation, the structure of GLUT1 remains unknown. Here we report the crystal structure of human GLUT1 at 3.2 Å resolution. The full-length protein, which has a canonical major facilitator superfamily fold, is captured in an inward-open conformation. This structure allows accurate mapping and potential mechanistic interpretation of disease-associated mutations in GLUT1. Structure-based analysis of these mutations provides an insight into the alternating access mechanism of GLUT1 and other members of the sugar porter subfamily. Structural comparison of the uniporter GLUT1 with its bacterial homologue XylE, a proton-coupled xylose symporter, allows examination of the transport mechanisms of both passive facilitators and active transporters.
- Sequence and structure of a human glucose transporter. Science 229, 941–945 (1985) et al.
- Glucose transporters in the 21st Century. Am. J. Physiol. Endocrinol. Metab. 298, E141–E145 (2010) &
- Reconstitution and purification of the D-glucose transporter from human erythrocytes. J. Biol. Chem. 252, 7384–7390 (1977) &
- Identification and characterization of the glucose transporter of the blood-brain barrier by cytochalasin B binding and immunological reactivity. Proc. Natl Acad. Sci. USA 81, 7233–7237 (1984) , , &
- Brain-type glucose transporter (GLUT-1) is selectively localized to the blood-brain barrier. Studies with quantitative western blotting and in situ hybridization. J. Biol. Chem. 265, 18035–18040 (1990) , &
- Glucose transporter proteins in brain. FASEB J. 8, 1003–1011 (1994) , &
- Defective glucose transport across brain tissue barriers: a newly recognized neurological syndrome. Neurochem. Res. 24, 587–594 (1999) et al.
- The expanding phenotype of GLUT1-deficiency syndrome. Brain Dev. 31, 545–552 (2009)
- Phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS). Curr. Neurol. Neurosci. Rep. 13, 342 (2013) , , , &
- 656 (Springer, 2011) , & Inborn Metabolic Diseases: Diagnosis and Treatment 5th edn
- GLUT1 deficiency syndrome into adulthood: a follow-up study. J. Neurol. 261, 589–599 (2014) et al.
- Early-onset absence epilepsy caused by mutations in the glucose transporter GLUT1. Ann. Neurol. 66, 415–419 (2009) et al.
- GLUT1 as a therapeutic target in hepatocellular carcinoma. Expert Opin. Ther. Targets 13, 1411–1427 (2009) &
- Analysis of a promoter polymorphism of the GLUT1 gene in patients with hepatocellular carcinoma. Mol. Membr. Biol. 28, 182–186 (2011) , , &
- GLUT1 expression is increased in hepatocellular carcinoma and promotes tumorigenesis. Am. J. Pathol. 174, 1544–1552 (2009) et al.
- Glucose transporter 1 (GLUT1) of anaerobic glycolysis as predictive and prognostic values in neoadjuvant chemoradiotherapy and laparoscopic surgery for locally advanced rectal cancer. Int. J. Colorectal Dis. 28, 375–383 (2013) et al.
- GLUT1 protein expression correlates with unfavourable histologic category and high risk in patients with neuroblastic tumours. Virchows Arch. 462, 203–209 (2013) , &
- Biomarkers in renal cell carcinoma. Curr. Opin. Urol. 19, 441–446 (2009) &
- Biological significance of F-FDG uptake on PET in patients with non-small-cell lung cancer. Lung Cancer 83, 197–204 (2014) et al.
- Mammalian and bacterial sugar transport proteins are homologous. Nature 325, 641–643 (1987) , , , &
- The ABCs of membrane transporters in health and disease (SLC series): introduction. Mol. Aspects Med. 34, 95–107 (2013) , , &
- Common folds and transport mechanisms of secondary active transporters. Annu. Rev. Biophys. 42, 51–72 (2013)
- This is about the in and the out. Nature Struct. Mol. Biol. 20, 654–655 (2013) &
- Major facilitator superfamily. Microbiol. Mol. Biol. Rev. 62, 1–34 (1998) , &
- Structural advances for the major facilitator superfamily (MFS) transporters. Trends Biochem. Sci. 38, 151–159 (2013)
- The alternating-access mechanism of MFS transporters arises from inverted-topology repeats. J. Mol. Biol. 407, 698–715 (2011) &
- Simple allosteric model for membrane pumps. Nature 211, 969–970 (1966)
- Crystal structure of a bacterial homologue of glucose transporters GLUT1–4. Nature 490, 361–366 (2012) et al.
- Structural basis for substrate transport in the GLUT-homology family of monosaccharide transporters. Nature Struct. Mol. Biol. 20, 766–768 (2013) , , , &
- Crystal structure of a glucose/H+ symporter and its mechanism of action. Proc. Natl Acad. Sci. USA 110, 17862–17867 (2013) , , , &
- 2008) & Lehninger Principles of Biochemistry (W. H. Freeman,
- Role of conserved arginine and glutamate residues on the cytosolic surface of glucose transporters for transporter function. Biochemistry 36, 12897–12902 (1997) et al.
- Lactose permease and the alternating access mechanism. Biochemistry 50, 9684–9693 (2011) , &
- Mutational analysis of GLUT1 (SLC2A1) in Glut-1 deficiency syndrome. Hum. Mutat. 16, 224–231 (2000) , &
- Autosomal dominant transmission of GLUT1 deficiency. Hum. Mol. Genet. 10, 63–68 (2001) et al.
- GLUT-1 deficiency without epilepsy–an exceptional case. J. Inherit. Metab. Dis. 26, 559–563 (2003) et al.
- Glut-1 deficiency syndrome: clinical, genetic, and therapeutic aspects. Ann. Neurol. 57, 111–118 (2005) et al.
- GLUT1 mutations are a cause of paroxysmal exertion-induced dyskinesias and induce hemolytic anemia by a cation leak. J. Clin. Invest. 118, 2157–2168 (2008) et al.
- GLUT1 gene mutations cause sporadic paroxysmal exercise-induced dyskinesias. Mov. Disord. 24, 1684–1688 (2009) et al.
- Glucose transporter-1 deficiency syndrome: the expanding clinical and genetic spectrum of a treatable disorder. Brain 133, 655–670 (2010) et al.
- Absence epilepsies with widely variable onset are a key feature of familial GLUT1 deficiency. Neurology 75, 432–440 (2010) , , , &
- Paroxysmal exercise-induced dyskinesia, writer’s cramp, migraine with aura and absence epilepsy in twin brothers with a novel SLC2A1 missense mutation. J. Neurol. Sci. 295, 110–113 (2010) et al.
- Excellent response to acetazolamide in a case of paroxysmal dyskinesias due to GLUT1-deficiency. J. Neurol. 258, 316–317 (2011) et al.
- GLUT1 mutations are a rare cause of familial idiopathic generalized epilepsy. Neurology 78, 557–562 (2012) et al.
- Functional architecture of MFS D-glucose transporters. Proc. Natl Acad. Sci. USA 111, E719–E727 (2014) , , &
- Structure of a fucose transporter in an outward-open conformation. Nature 467, 734–738 (2010) et al.
- 1978) David Keilin’s respiratory chain concept and its chemiosmotic consequences. In Nobel Lectures, Chemistry 1971–1980 (ed. ) (World Scientific Publishing Co.,
- Effect of the D32N and N300F mutations on the activity of the bacterial sugar transport protein, GalP. Biochem. Soc. Trans. 26, S306 (1998) , , &
- Structural biology: Bundles of insights into sugar transporters. Nature 490, 348–350 (2012) &
- The PyMOL Molecular Graphics System. http://www.pymol.org (2002)
- Processing of X-ray diffraction data. Methods Enzymol. 276, 307–326 (1997) &
- The CCP4 suite: programs for protein crystallography. Acta Crystallogr. D 50, 760–763 (1994)
- Phaser crystallographic software. J. Appl. Crystogr. 40, 658–674 (2007) et al.
- CHAINSAW: a program for mutating pdb files used as templates in molecular replacement. J. Appl. Crystallogr. 41, 641–643 (2008)
- Coot: model-building tools for molecular graphics. Acta Crystallogr. D 60, 2126–2132 (2004) &
- PHENIX: building new software for automated crystallographic structure determination. Acta Crystallogr. D 58, 1948–1954 (2002) et al.
- Childhood chorea with cerebral hypotrophy: a treatable GLUT1 energy failure syndrome. Arch. Neurol. 66, 1410 (2009) et al.
- Imaging the metabolic footprint of Glut1 deficiency on the brain. Ann. Neurol. 52, 458–464 (2002) , , , &
- Mild adolescent/adult onset epilepsy and paroxysmal exercise-induced dyskinesia due to GLUT1 deficiency. Epilepsia 51, 2466–2469 (2010) et al.
- Autosomal recessive inheritance of GLUT1 deficiency syndrome. Neuropediatrics 40, 207–210 (2009) et al.
Extended data figures and tables
Extended Data Figures
- Extended Data Figure 1: Structure determination of GLUT1. (964 KB)
a, The 2Fo − Fc electron density map. The stereo-view map for one representative slab, shown as cyan mesh, is contoured at 1.0σ. b, The crystal packing of GLUT1 in the space group C2. Each GLUT1 molecule is shown as rainbow-coloured ribbon, blue and red for the N and C termini, respectively.
- Extended Data Figure 2: One β-NG molecule occupies the substrate-binding site of the inward-open GLUT1. (829 KB)
a, The ‘omit’ electron density observed in the inward-open cavity of GLUT1. The electron density, shown as magenta mesh, is contoured at 3.0σ. The N, C and ICH domains are coloured green, blue and yellow, respectively. b, A β-NG molecule fits well into the electron density inside the cavity. The 2Fo − Fc electron density map (cyan mesh) for the β-NG molecule is contoured at 1.0σ. c, The overall GLUT1 structure with the bound β-NG molecule. β-NG is represented by white spheres. d, The coordination of the sugar moiety of β-NG by GLUT1 is similar to the binding of d-glucose by XylE. The structures of GLUT1 (blue) and XylE (cyan) are superimposed relative to their respective C domains. The ligands are shown in stick representation. Despite the similarity between d-glucose and β-NG, we cannot exclude the possibility that presence of the aliphatic tail of β-NG in GLUT1 may subtly affect positioning of the sugar moiety compared to d-glucose. e, Coordination of the d-glucopyranoside of β-NG by GLUT1. The d-glucopyranoside of β-NG is hydrogen-bonded to the surrounding polar residues in the C domain, including Gln 282/Gln 283/Asn 288 from TM7, Asn 317 from TM8, and Asn 415 from TM11. The residues whose mutations are associated with GLUT1 deficiency syndrome are labelled in magenta.
- Extended Data Figure 3: Interactions between the N and C domains observed in the inward-open GLUT1 and the outward-facing XylE. (577 KB)
a, In GLUT1, the inter-domain contacts, mainly on the extracellular side, include both van der Waals interactions and hydrogen bonds. Residues whose mutations are associated with GLUT1 deficiency syndrome are labelled in magenta. b, In XylE, there are only limited interactions between the N and C domains at the transmembrane region.
- Extended Data Figure 4: Conformational differences between GLUT1 and XylE. (460 KB)
a, Structural comparison of the inward-open GLUT1 and the outward-facing, partly occluded, ligand-bound XylE. Similar intracellular views are shown for GLUT1 and XylE. Note that the C-terminal helix IC5, which was referred to as IC4 in a previous study of XylE (ref. 28), is invisible in the structure of GLUT1 probably due to its inherent flexibility in this conformation. b, c, Structural superimpositions of GLUT1 and XylE relative to their respective N domains (b) and C domains (c). A detailed analysis can be found in Figs 3 and 4. d, Conformational differences of TM7 between GLUT1 and XylE. Compared to that in XylE, the extracellular segment of TM7 in GLUT1 is further bent away from the transport path.
- Extended Data Figure 5: Sequence alignment of GLUT1-4 with XylE. (746 KB)
Secondary structural elements of GLUT1 are indicated above the sequence alignment. Invariant and highly conserved amino acids are shaded yellow and grey, respectively. The conserved sugar porter family signature motifs are underscored with red lines. The residues that are hydrogen-bonded to d-glucose in XylE are shaded red. The GLUT1 residues whose mutations were found in GLUT1 deficiency syndrome are indicated by black circles above. The sequences were aligned with ClustalW.