The long term goal of this proposal is to identify the molecular defect(s) underlying the insulin-resistance seen in human diabetes and obesity. More immediate goals are to understand the molecular mechanisms how the facilitative glucose transporters, a family in intrinsic transmembrane proteins, catalyze translocation of selected sugar molecules. We will use purified human erythrocyte glucose transporter (HEGT) and study its tertiar structure, particularly that of putative glucose channel. A hydropathy analysis of the amino acid sequence of this protein predicts that it contains a transmembrane domain made of twelve transmembrane segments, five of which are amphipathic and may line the purported aqueous channel. It also contains three intracellular and one extracellular nonmembrane domains We use this prediction as a working model in determining the channel structure. We will determine which of these twelve transmembrane segments are positioned in contact with the lipid bilayer, and which the aqueous channel. We will first establish the basic chemical methodology required for the studies. This will include separation and identification of the twelve transmembrane segments. To determine the native tertiary structure of these transmembrane segments. We will chemically crosslink and identify neighboring transmembrane segments, and identify the channel-forming segments and nonchannel-forming segments by measuring the accessibility of segments to transportable, covalently active glucose analogs (4ADG and 6ADG and lipophilic covalent probes, respectively, Based on these data, we will deduce the overall structure of the transmembrane domain. There are strong indication for the importance of intrinsic activity- regulation of glucose transporter function in glucose homeostasis in normal and diseased states. Understanding of this regulation of the intrinsic activity at the molecular level would be greatly assisted once we understan the tertiary structure of the glucose channel as proposed here.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK013376-23
Application #
2136779
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Project Start
1978-07-01
Project End
1996-06-30
Budget Start
1994-07-01
Budget End
1996-06-30
Support Year
23
Fiscal Year
1994
Total Cost
Indirect Cost
Name
State University of New York at Buffalo
Department
Physiology
Type
Schools of Medicine
DUNS #
038633251
City
Buffalo
State
NY
Country
United States
Zip Code
14260
Hah, J S; Ryu, J W; Lee, W et al. (2002) Transient changes in four GLUT4 compartments in rat adipocytes during the transition, insulin-stimulated to basal: implications for the GLUT4 trafficking pathway. Biochemistry 41:14364-71
Ryu, Jiwon; Hah, Jong Sik; Park, James S S et al. (2002) Protein kinase C-zeta phosphorylates insulin-responsive aminopeptidase in vitro at Ser-80 and Ser-91. Arch Biochem Biophys 403:71-82
Hah, Jong Sik; Ryu, Jiwon; Lee, Wan et al. (2002) The hepatocyte glucose-6-phosphatase subcomponent T3: its relationship to GLUT2. Biochim Biophys Acta 1564:198-206
Epand, R F; Epand, R M; Jung, C Y (2001) Ligand-modulation of the stability of the glucose transporter GLUT 1. Protein Sci 10:1363-9
Lachaal, M; Spangler, R A; Jung, C Y (2001) Adenosine and adenosine triphosphate modulate the substrate binding affinity of glucose transporter GLUT1 in vitro. Biochim Biophys Acta 1511:123-33
Lee, W; Ryu, J; Hah, J et al. (2000) Association of carboxyl esterase with facilitative glucose transporter isoform 4 (GLUT4) intracellular compartments in rat adipocytes and its possible role in insulin-induced GLUT4 recruitment. J Biol Chem 275:10041-6
Lee, W; Ryu, J; Spangler, R A et al. (2000) Modulation of GLUT4 and GLUT1 recycling by insulin in rat adipocytes: kinetic analysis based on the involvement of multiple intracellular compartments. Biochemistry 39:9358-66
Lee, W; Ryu, J; Souto, R P et al. (1999) Separation and partial characterization of three distinct intracellular GLUT4 compartments in rat adipocytes. Subcellular fractionation without homogenization. J Biol Chem 274:37755-62
Shi, Y; Samuel, S J; Lee, W et al. (1999) Cloning of an L-3-hydroxyacyl-CoA dehydrogenase that interacts with the GLUT4 C-terminus. Arch Biochem Biophys 363:323-32
Zeng, H; Parthasarathy, R; Rampal, A L et al. (1996) Proposed structure of putative glucose channel in GLUT1 facilitative glucose transporter. Biophys J 70:14-21

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