LOCALIZATION OF TRANSFERRIN RECEPTORS AND INSULIN-LIKE GROWTH FACTOR-II RECEPTORS IN VESICLES FROM 3T3-L1 ADIPOCYTES THAT CONTAIN INTRACELLULAR GLUCOSE TRANSPORTERS
LOCALIZATION OF TRANSFERRIN RECEPTORS AND INSULIN-LIKE GROWTH FACTOR-II RECEPTORS IN VESICLES FROM 3T3-L1 ADIPOCYTES THAT CONTAIN INTRACELLULAR GLUCOSE TRANSPORTERS
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DOI：
10.1083/jcb.108.4.1537
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发表时间：
1989-04-01
影响因子：
7.8
通讯作者：
LIENHARD, GE
中科院分区：
文献类型：
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作者：
TANNER, LI;LIENHARD, GE
用结合法测定3T3-L1脂肪细胞制备的亚细胞膜组分洗涤剂提取物中的转铁蛋白受体。与对照细胞的相应组分相比，由胰岛素处理的细胞制备的粗质膜组分中受体的数量虽小但显著增加（1.2倍），而微粒体膜中转铁蛋白受体的数量减少了40%。含有胰岛素反应性葡萄糖转运体（GT）的细胞内囊泡已通过免疫吸附从微粒体部分分离出来（Biber， J. W.和G. E. Lienhard. 1986）。生物。化学261:16180 - 16184)。这部分中所有的转铁蛋白受体都位于这些囊泡中；然而，由于GT囊泡含有。apprx。转铁蛋白受体是GT的30倍，平均每三个囊泡中只有一个含有转铁蛋白受体。125i -五芒糖6-磷酸BSA与3T3-L1脂肪细胞在4度的结合。C用于监测表面胰岛素样生长因子II (IGF-II)/甘露糖6-磷酸受体。将细胞暴露在37度的胰岛素中。C作用5分钟，表面受体增加2.5-4.5倍。免疫印迹法检测，胰岛素处理细胞制备的微粒体膜中IGF-II受体的数量相应减少20%。此外，IGF-II受体和GT位于相同的细胞内囊泡中，因为免疫吸附的囊泡中含有70-95%的两种蛋白质的羧基端肽抗体最初存在于微粒体部分。结合其他研究，这些结果表明，在3T3-L1脂肪细胞中，三种膜蛋白（GT，转铁蛋白受体和IGF-II受体）对胰岛素的反应类似，通过从它们共定位的细胞内腔室重新分布到表面。
Transferrin receptors in detergent extracts of subcellular membrane fractions prepared from 3T3-L1 adipocytes were measured by a binding assay. There was a small but significant increase (1.2-fold) in the amount of receptor in a crude plasma membrane fraction and a 40% decrease in the number of transferrin receptors in microsomal membranes prepared from insulin-treated cells, when compared with corresponding fractions from control cells. Intracellular vesicles containing insulin-responsive glucose transporters (GT) have been isolated by immunoadsorption from the microsomal fraction (Biber, J. W., and G. E. Lienhard. 1986. J. Biol. Chem. 261:16180-16184). All of the transferrin receptors in this fraction were localized in these vesicles; however, because the GT vesicles contain .apprx. 30-fold transferrin receptors than GT, on the average only one vesicle in three contains a transferrin receptor. The binding of 125I-pentamannose 6-phosphate BSA to 3T3-L1 adipocytes at 4.degree. C was used to monitor surface insulin-like growth factor II (IGF-II)/mannose 6-phosphate receptors. Exposure of cells to insulin at 37.degree. C for 5 min resulted in a 2.5-4.5-fold increase in surface receptors. There was a corresponding 20% decrease in the amount of IGF-II receptors in the microsomal membranes prepared from insulin-treated cells, as assayed by immunoblotting. Moreover, the IGF-II receptors and GT were located in the same intracellular vesicles, since antibodies to the carboxyterminal peptide of either protein immunoadsorbed vesicles containing 70-95% of both proteins initially present in the microsomal fraction. In conjunction with other studies, these results indicate that in 3T3-L1 adipocytes, three membrane proteins (the GT, the transferrin receptor, and the IGF-II receptor) respond similarly to insulin, by redistributing to the surface from intracellular compartment(s) in which they are colocalized.