EXPRESSION OF HUMAN GLUCOSE TRANSPORTERS IN XENOPUS OOCYTES - KINETIC CHARACTERIZATION AND SUBSTRATE SPECIFICITIES OF THE ERYTHROCYTE, LIVER, AND BRAIN ISOFORMS
EXPRESSION OF HUMAN GLUCOSE TRANSPORTERS IN XENOPUS OOCYTES - KINETIC CHARACTERIZATION AND SUBSTRATE SPECIFICITIES OF THE ERYTHROCYTE, LIVER, AND BRAIN ISOFORMS
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DOI：
10.1021/bi00235a004
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发表时间：
1991-05-28
期刊：
影响因子：
2.9
通讯作者：
BELL, GI
中科院分区：
文献类型：
--
作者：
GOULD, GW;THOMAS, HM;BELL, GI
我们描述了人类葡萄糖转运蛋白家族中的三个成员，即红细胞型转运蛋白(GLUT 1)、肝型转运蛋白(GLUT 2)和脑型转运蛋白(GLUT 3)的功能表达，方法是将相应的mRNAs注射到非洲爪哇卵母细胞中。通过3-O-甲基-D-葡萄糖或2-脱氧-D-葡萄糖的转运来衡量转运活性。我们测量了葡萄糖1、2和3的3-O-甲基-D-葡萄糖的K(M)，并根据这些不同的转运蛋白在血糖调节中的可能作用对结果进行了讨论。还检测了这些转运蛋白异构体的底物特异性。我们发现，对于所有的转运蛋白，2-脱氧-D-葡萄糖的转运都被D-抑制，但不被L-葡萄糖抑制。此外，D-半乳糖和D-甘露糖都被葡萄糖1-3以显著的速率转运；此外，GLUT 2能够转运D-果糖。用己糖抑制2-脱氧-D-葡萄糖摄取的方法研究了谷氨酰胺1-3的葡萄糖结合位点的性质。我们表明，这种抑制的特征对于每种转运蛋白亚型是不同的。
We describe the functional expression of three members of the family of human facilitative glucose transporters, the erythrocyte-type transporter (GLUT 1), the liver-type transporter (GLUT 2), and the brain-type transporter (GLUT 3), by microinjection of their corresponding mRNAs into Xenopus oocytes. Expression was determined by the appearance of transport activity, as measured by the transport of 3-O-methyl-D-glucose or 2-deoxy-D-glucose. We have measured the K(m) for 3-O-methyl-D-glucose of GLUTs 1, 2, and 3, and the results are discussed in light of the possible roles for these different transporters in the regulation of blood glucose. The substrate specificity of these transporter isoforms has also been examined. We show that, for all transporters, the transport of 2-deoxy-D-glucose is inhibited by D- but not by L-glucose. In addition, both D-galactose and D-mannose are transported by GLUTs 1-3 at significant rates; furthermore, GLUT 2 is capable of transporting D-fructose. The nature of the glucose binding sites of GLUTs 1-3 was investigated by using hexose inhibition of 2-deoxy-D-glucose uptake. We show that the characteristics of this inhibition are different for each transporter isoform.