Blok J, Gibbs E M, Lienhard G E, Slot J W, Geuze H J
Department of Cell Biology, State University of Utrecht, The Netherlands.
J Cell Biol. 1988 Jan;106(1):69-76. doi: 10.1083/jcb.106.1.69.
A semiquantitative method using immunocytochemistry on ultrathin cryosections and the protein A-gold technique was performed to study the effect of insulin on the cellular distribution of the glucose transporters in cultured 3T3-L1 adipocytes. In basal cells a substantial portion of the label was present in a tubulovesicular structure at the trans side of the Golgi apparatus, likely to represent the trans-Golgi reticulum, and in small vesicles present in the cytoplasm. Treatment with insulin induced a rapid translocation of transporters from the tubulovesicular structure to the plasma membrane. The transporter labeling of the plasma membrane increased three-fold and that of the tubulovesicular structure decreased by half. There was no effect of insulin on the degree of label in the small cytoplasmic vesicles. Removal of insulin from stimulated cells rapidly reversed the distribution of transporters to that seen in basal cells. This study thus provides the first morphological evidence for the occurrence of transporter translocation in insulin action and identifies for the first time the intracellular location of the responsive transporters.
采用超薄冰冻切片免疫细胞化学和蛋白A-金技术的半定量方法，研究胰岛素对培养的3T3-L1脂肪细胞中葡萄糖转运体细胞分布的影响。在基础细胞中，大部分标记物存在于高尔基体反面的管状囊泡结构中，可能代表反式高尔基体网状结构，以及存在于细胞质中的小泡中。胰岛素处理诱导转运体从管状囊泡结构迅速转运至质膜。质膜的转运体标记增加了三倍，而管状囊泡结构的标记减少了一半。胰岛素对小细胞质囊泡中的标记程度没有影响。从受刺激的细胞中去除胰岛素后，转运体的分布迅速恢复到基础细胞中的状态。因此，本研究首次提供了胰岛素作用中转运体易位发生的形态学证据，并首次确定了反应性转运体的细胞内位置。
