Postdoctoral Position Available

Lab Page Link

Anthony Carruthers, Ph.D.

Academic Role: Professor

Faculty Appointment(s) In:
   Biochemistry and Molecular Pharmacology
   Physiology

Other Affiliation(s):
   Center for AIDS Research
   Graduate School of Biomedical Sciences

Carrier-mediated transport

Research in my laboratory is aimed at understanding protein-mediated transport of nutrients and other small molecules across cell membranes.

The Major Facilitator Superfamily (MFS) of transport proteins comprises more than 1,000 unique proteins that mediate passive and secondary active transmembrane transport of nutrients, drugs, ions, neurotransmitters, and other molecules in all organisms. The facilitative glucose transporter family (GLUT1-12 and HMIT) mediates monosaccharide uniport in vertebrates. GLUT proteins are expressed in an organ-system specific manner allowing them to meet the metabolic needs of the organism. For example, GLUT2 is found in the liver and β-cells of the pancreas, GLUT3 is expressed in neuronal cells, and insulin-sensitive GLUT4 is found in muscle and adipose tissue. GLUT1 is found in many tissues throughout the body but is expressed most highly in the circulatory system and at blood-tissue barriers such as the blood-brain barrier where it mediates glucose transfer from blood to brain by catalyzing transcellular glucose transport. The focus of our laboratory is to understand the molecular basis of GLUT function and regulation.

Our methods include the latest techniques in molecular biology, genetics, protein chemistry, mass spectrometry, biochemistry, biophysics and cellular physiology. More details about the laboratory may be found at our lab web page http://glutxi.umassmed.edu/.

Figures

Ultrastructure of Human Erythrocyte GLUT1

Analysis of GLUT1 aggregation state by freeze-fracture electron microscopy. High magnification of unidirectionally shadowed freeze-fractured electron micrographs of GLUT1 proteoliposomes. Composite of nonreduced (left) and reduced (middle), purified GLUT1 Integral Membrane Particles. The bar represents 10 nm. The images represent the average of 60 particles. The rightmost image shows the dimensions of monomeric GLUT1 threaded through GlpT structure.

Structural basis of GLUT1 regulation by ATP

ATP regulation of GLUT1. GLUT1 membrane spanning topography is illustrated. GLUT1 behavior is illustrated in the presence of AMP (left) or ATP (right). Trypsin cleavage sites (yellow and brown circles), sites of antibody recognition (green and red sequence), and sites where IgG binding is not detected (blue sequence) are indicated. In the presence of ATP (right), ATP-sensitive (red sequence) and insensitive (green sequence) IgG binding domains are also indicated. The circles show ATP-insensitive tryptic cleavage sites (yellow circles), ATP-protected tryptic cleavage sites (brown circles), and ATP-protected sites of lysine covalent modification by Sulfo-NHS-LC-Biotin (red circles). We propose that the GLUT1 C-terminus and the C-terminal half of the middle loop interact in response to ATP binding. This reduces their respective accessibility to polar reagents and restricts glucose release from the translocation pathway.

Recent Publications

(Graduate students in bold-face)

Leitch, J. M., and A. Carruthers. 2007. ATP-dependent sugar transport complexity in human erythrocytes. Am J Physiol Cell Physiol S 292:C974-86.

Simpson, I. A., A. Carruthers, and S. J. Vannucci. 2007. Supply and demand in cerebral energy metabolism: the role of nutrient transporters. J Cereb Blood Flow Metab (http://www.nature.com/jcbfm/journal/vaop/ncurrent/abs/9600521a.html;jsessionid=88FF2F7D1B8A35BDA523FDA7640DAD18)

Blodgett, D. M., J. K. De Zutter, K. B. Levine, P. Karim, and A. Carruthers. 2007. Structural Basis of GLUT1 Inhibition by Cytoplasmic ATP. J Gen Physiol 130:157-168.

Friedman, J. R., E. A. Thiele, D. Wang, K. B. Levine, E. K. Cloherty, H. H. Pfeifer, D. C. De Vivo, A. Carruthers, and M. R. Natowicz. 2006. Atypical GLUT1 deficiency with prominent movement disorder responsive to ketogenic diet. Mov Disord 21:241-244.

Graybill, C., A. N. van Hoek, D. Desai, A. M. Carruthers, and A. Carruthers. 2006. Ultrastructure of Human Erythrocyte GLUT1. Biochemistry 45:8096-8107.

Levine, K. B., T. K. Robichaud, S. Hamill, L. A. Sultzman, and A. Carruthers. 2005. Properties of the human erythrocyte glucose transport protein are determined by cellular context. Biochemistry 44:5606-5616.

Blodgett, D. M., and A. Carruthers. 2005. Quench-Flow Analysis Reveals Multiple Phases of GluT1-Mediated Sugar Transport. Biochemistry 44:2650-2660.

Blodgett, D. M., and A. Carruthers. 2004. Conventional transport assays underestimate sugar transport rates in human red cells. Blood Cells Mol Dis 32:401-407.

Levine, K. B., and A. Carruthers. 2004. Regulation of carrier-mediated sugar transport by transporter quaternary structure. In Topics in Current Genetics Molecular mechanisms controling transmembrane transport(9). E. Boles, and R. Krämer, eds. p. 67.

Levine, K. B., E. K. Cloherty, S. Hamill, and A. Carruthers. 2002. Molecular determinants of sugar transport regulation by ATP. Biochemistry 41:12629-12638.

Cloherty, E. K., K. B. Levine, C. Graybill, and A. Carruthers. 2002. Cooperative nucleotide binding to the human erythrocyte sugar transporter. Biochemistry 41:12639-12651.

Heard, K. S., N. Fidyk, and A. Carruthers. 2000. ATP-dependent substrate occlusion by the human erythrocyte sugar transporter. Biochemistry 39:3005-3014.

Sultzman, L. A., and A. Carruthers. 1999. Stop-flow analysis of cooperative interactions between GLUT1 sugar import and export sites. Biochemistry Biochemistry 38:6640-6650.

Levine, K. B., E. K. Cloherty, N. J. Fidyk, and A. Carruthers. 1998. Structural and physiologic determinants of human erythrocyte sugar transport regulation by adenosine triphosphate. Biochemistry 37:12221-12232.

Heard, K. S., M. Diguette, A. C. Heard, and A. Carruthers. 1998. Membrane-bound glyceraldehyde-3-phosphate dehydrogenase and multiphasic erythrocyte sugar transport. Exp Physiol 83:195-201.

Cloherty, E. K., D. L. Diamond, K. S. Heard, and A. Carruthers. 1996. Regulation of GLUT1-mediated sugar transport by an antiport/uniport switch mechanism. Biochemistry 35:13231-13239.

Carruthers, A., and R. J. Zottola. 1996. Erythrocyte sugar transport. In Handbook of Biological Physics. "Transport Processes in Eukaryotic and Prokaryotic Organisms".(2). H. R. K. J. S. L. W.N. Konings, ed. Elsevier, Amsterdam, p. pp 311.

Cloherty, E. K., K. S. Heard, and A. Carruthers. 1996. Human erythrocyte sugar transport is incompatible with available carrier models. Biochemistry 35:10411-10421.

Zottola, R. J., E. K. Cloherty, P. E. Coderre, A. Hansen, D. N. Hebert, and A. Carruthers. 1995. Glucose transporter function is controlled by transporter oligomeric structure. A single, intramolecular disulfide promotes GLUT1 tetramerization. Biochemistry 34:9734-9747.

Potential Rotation Projects

Project 1                Mapping glucose transporter ligand binding sites.

Project 2                Does the glucose transporter contain an internal disulfide bridge?

Project 3                Mapping intramolecular contacts within GLUT1.

Project 4                How does cell shape regulate glucose transport?

Project 5                Is there a glucose-dependent membrane ATPase?

Project 6                Is the glucose transporter asymmetric at physiological temperature?

Project 7                Using transporter chimeras to map specificity and functional domains.

For specific details on each project, please e-mail me at:

                                anthony.carruthers@umassmed.edu

Laboratory Personnel

Graduate Students

Anthony Cura
Trista Robichaud

Postdoctoral Fellows

Julie DeZutter
David Blodgett

Academic Background

Tony Carruthers received his B.Sc. degree from the University of Manchester (U.K.) in 1977 and his Ph.D. in cellular physiology from King's College, London, in 1980. In 1982 he received a Wellcome Trust Travel Award and a NATO Overseas Postdoctoral Fellowship to perform postdoctoral work at the University of Massachusetts Medical Center.

Following his postdoctoral work, he remained at UMass Medical School as a faculty member in the Department of Biochemistry and Molecular Pharmacology and the Department of Physiology.

Office: S1-842B
Phone: 508-856-6074 & 5570
Fax: 508-856-3659 or 508-856-6464
E-mail: Anthony.Carruthers@umassmed.edu
Keywords: Biophysics, Cell Biology, Biochemistry, Structural Biology

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Postdoctoral Position Available A postdoctoral position is available in this laboratory to study sugar transporter biology.  Contact Dr. Anthony Carruthers for more details.