| Project/Area Number |
14570112
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General medical chemistry
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| Research Institution | Teikyo University |
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Principal Investigator |
KASAHARA Toshiko Teikyo University, School of Medicine, Lecturer, 医学部, 講師 (60328086)
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| Co-Investigator(Kenkyū-buntansha) |
豊福 恭子 帝京大学, 医学部, 博士研究員
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 2003: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Glucose transporter / Chimera / Substrate recognition / Yeast / GLUT / Glut |
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| Research Abstract |
The yeast Saccharomyces cerevisiae takes up glucose over a wide range of exiracellular concentrations with the use of abundant hexose transporters (Hxt 1-17, Gal2). They contain 12 transmembrane segments (TMs), and members of the major facilitator superfamily, to which human facilitative glucose transporters belong.
Chimeras of Hxt2 and Hxt1 high-affinity and low-affinity glucose transporters, respectively were constructed by randomly replacing each of the I2TMs of Hxt2 with the corresponding segment of Hxt1 (TM shuffling). Characterization of these chimeras revealed that at least TMs 1, 5, 7 and 8 of Hxt2 are required for high-affinity transport activity.
To determine which amino acid residues in these TMs are important for high-affinity glucose transport, we systematically shuffled all the 20 residues in these regions that differ between Hxt2 and Hxt1. Analysis of 60 independent mutant strains identified as expressing high-affinity and high-capacity glucose. transport activity by selection on glucose-limited agar plates revealed that Leu-20 I in TM5 of Hxt2 is most important.
Human GLUT I also has Leu at the corresponding site to Leu-20 I of Hxt2, strongly indicating that this Leu contributes to determine affinity for substrate.
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