GLUT2 IS THE TRANSPORTER FOR FRUCTOSE ACROSS THE RAT INTESTINAL BASOLATERAL MEMBRANE
GLUT2 IS THE TRANSPORTER FOR FRUCTOSE ACROSS THE RAT INTESTINAL BASOLATERAL MEMBRANE
复制标题
DOI：
10.1016/0016-5085(93)90948-c
复制
发表时间：
1993-10-01
期刊：
影响因子：
29.4
通讯作者：
CHEESEMAN, CI
中科院分区：
文献类型：
--
作者：
CHEESEMAN, CI
背景：刷状缘膜中的二硫键合酶和GLUT 5以及基底外侧膜中的GLUT 2在果糖跨肠吸收中的确切作用尚未完全确定。本文介绍了表征果糖运输跨空肠基底外侧membranes.Methods：运输果糖测定使用快速过滤囊泡。在囊泡制备之前用葡萄糖和果糖进行体内管腔灌注用于评估GLUT 2活性的调节。结果：果糖的最大转运速率为1100 pmol/mg蛋白/s，米氏常数为16 mmol/L。果糖和葡萄糖可以完全抑制彼此的转运。灌流的肠腔与果糖或葡萄糖盐水4小时产生了四倍的最大fructose transport.Conclusions：这些数据表明，一个运输蛋白，GLUT 2，是负责移动果糖和葡萄糖的肠上皮细胞跨基底外侧膜在基础条件下。这种或密切相关的载体的活性通过肠腔中己糖的存在而迅速上调，解释了管腔葡萄糖对果糖吸收的增强作用，并且避免了涉及顶端二硫键苷酶的任何需要。
Background:The exact roles of disaccharidases and GLUT5 in the brush border membrane and GLUT2 in the basolateral membrane in the absorption of fructose across the intestine have not been fully determined. This paper describes characterization of fructose transport across the jejunal basolateral membrane using isolated membrane vesicles.Methods:Transport of fructose was measured using rapid filtration of vesicles. Luminal perfusion in vivo with glucose and fructose before vesicle preparation was used to assess modulation of GLUT2 activity. Western blotting measured the abundance of GLUT2 in the membrane.Results:The maximal rate of transport for fructose was 1100 pmol/mg protein/s and the Michaelis constant was 16 mmol/L. Fructose and glucose could completely inhibit the transport of each other. Perfusion of the intestinal lumen with fructose or glucose saline for 4 hours produced a fourfold increase in maximal fructose transport.Conclusions:These data indicate that the one transport protein, GLUT2, is responsible for moving both fructose and glucose out of the enterocyte across the basolateral membrane under basal conditions. The activity of this, or a closely related carrier, is rapidly upregulated by the presence of hexoses in the intestinal lumen, explaining the potentiation of fructose absorption by luminal glucose and obviating any need to involve apical disaccharidases.