1993 Fiscal Year Final Research Report Summary
Molecular manipulations to probe the relationship between structure and function of the glucose transporter
| Project/Area Number |
04454557
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
内分泌・代謝学
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| Research Institution | University of Tokyo |
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Principal Investigator |
OKA Yoshitomo THIRD DEPARTMENT OF INTERNAL MEDICINE FACULTY OF MEDICINE, UNIVERSITY OF TOKYO ASSISTANT PROFESSOR, 医学部・附属病院, 助手 (70175256)
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| Co-Investigator(Kenkyū-buntansha) |
INUKAI Kouichi THIRD DEPARTMENT OF INTERNAL MEDICINE FACULTY OF MEDICINE, UNIVERSITY OF TOKYO R, 医学部・附属病院, 医員
ISHIHARA Hisamitu THIRD DEPARTMENT OF INTERNAL MEDICINE FACULTY OF MEDICINE, UNIVERSITY OF TOKYO R, 医学部・附属病院, 医員
KATAGIRI Hideki THIRD DEPARTMENT OF INTERNAL MEDICINE FACULTY OF MEDICINE, UNIVERSITY OF TOKYO R, 医学部・附属病院, 医員
ASANO Tomoichiro THIRD DEPARTMENT OF INTERNAL MEDICINE FACULTY OF MEDICINE, UNIVERSITY OF TOKYO R, 医学部・附属病院, 助手 (70242063)
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| Project Period (FY) |
1992 – 1993
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| Keywords | glucose transporter / structure and function / chimera |
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| Research Abstract |
Recent cDNA cloning has disclosed the presence of a structurally related family of proteins that catalize facilitated glucose transporter across the plasma membranes. However, in spite of the marked similarity in structure, the tissue distribution and subcellular distribution, as well as characteristics of glucose transport, are different among isoforms. We have focused on a C-terminal domain, since it is diverse in size and amino acid sequence among glucose transporter isoforms. GLUT2 has far higher Km and Vmax values compared with GLUT1. To investigate the role pf the intracellular C-terminal domain in glucose transport, we expressed in Chinese hamster ovary cells the mutated GLUT1 whose intracellular C-terminal domain was replaced with that of GLUT2 by means of engineering the chimeric cDNA.Cytochalasin B, for which GLUT2 protein has much lower affinity, bound to this chimeric protein in a fashion similar to GLUT1. In contrast, greater transport activity was observed in this chimeric glucose transporter compared with the wild-type GLUT1 at 10 mM 2-deoxy-D-glucose concentration. The kinetic studies on 2-deoxy-D-glucose uptake revealed a 3.8-fold increase in Km and a 4.3-fold increase in Vmax in this chimeric glucose transporter compared with the wild-type GLUT1. Thus, replacement of the intracellular C-terminal domain confers the GLUT2-like property on the glucose transporter. These results strongly suggest that the diversity of intracellular C-terminal domain contributes to the diversity of glucose transport characteristics among isoforms.
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