Inukai K, Asano T, Katagiri H, Ishihara H, Anai M, Fukushima Y, Tsukuda K, Kikuchi M, Yazaki Y, Oka Y
Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Endocrinology. 1993 Nov;133(5):2009-14. doi: 10.1210/endo.133.5.8404647.
We have isolated a clone from the rat jejunum cDNA library using a fragment of human GLUT5 cDNA as a probe. The coding region of this clone shares 80% nucleotide and 81% amino acid identity with human GLUT5 and is thus termed rat GLUT5 cDNA. Rat GLUT5 mRNA exhibited a tissue distribution very similar to that of human GLUT5, with the highest levels in the jejunum, but was not detected in fat, muscle, or testis on Northern blot analysis. The antipeptide antibody raised against the C-terminal domain of rat GLUT5 protein specifically recognized a rat jejunal protein with an apparent mol wt of 60,000 on immunoblots. The amount of GLUT5 mRNA and protein in the jejuni of rats fed a fructose-enriched diet (50%, wt/wt) for 3 days were increased 2.5- and 6-fold, respectively, compared to those of rats fed standard rat chow, whereas those of rats fed a starch-enriched diet (50%, wt/wt) were not altered. Similarly, GLUT5 mRNA and protein in the jejunum were increased 5- and 8-fold, respectively, after 15 days of fructose feeding. Thus, an increase in fructose absorption up-regulates GLUT5 expression in the jejunum. These results are consistent with the notion that GLUT5 plays a major role in fructose absorption in the small intestine.
我们使用人GLUT5 cDNA片段作为探针，从大鼠空肠cDNA文库中分离出一个克隆。该克隆的编码区与人类GLUT5的核苷酸同源性为80%，氨基酸同源性为81%，因此被命名为大鼠GLUT5 cDNA。大鼠GLUT5 mRNA的组织分布与人GLUT5非常相似，在空肠中水平最高，但在Northern印迹分析中，在脂肪、肌肉或睾丸中未检测到。针对大鼠GLUT5蛋白C末端结构域产生的抗肽抗体在免疫印迹中特异性识别一种表观分子量为60,000的大鼠空肠蛋白。与喂食标准大鼠饲料的大鼠相比，喂食富含果糖饮食（50%，重量/重量）3天的大鼠空肠中GLUT5 mRNA和蛋白的量分别增加了2.5倍和6倍，而喂食富含淀粉饮食（50%，重量/重量）的大鼠则没有变化。同样，果糖喂养15天后，空肠中的GLUT5 mRNA和蛋白分别增加了5倍和8倍。因此，果糖吸收的增加上调了空肠中GLUT5的表达。这些结果与GLUT5在小肠果糖吸收中起主要作用的观点一致。
