Zorzano A, Wilkinson W, Kotliar N, Thoidis G, Wadzinkski B E, Ruoho A E, Pilch P F
Department of Biochemistry, Boston University School of Medicine, Massachusetts 02118.
J Biol Chem. 1989 Jul 25;264(21):12358-63.
We have recently described a monoclonal antibody (1F8) that recognizes a form of glucose transporter unique to fat and muscle (James, D. E., Brown, R., Navarro, J., and Pilch, P. F. (1988) Nature 333, 183-185), tissues that respond acutely to insulin by markedly increasing their glucose uptake. Here, we report that rat adipocytes possess two immunologically distinct glucose-transporters: one recognized by 1F8, and one reactive with antibodies raised against the human erythrocyte glucose transporter. Immunoadsorption experiments indicate that these glucose transporters reside in different vesicle populations and that both transporter isoforms translocate from intracellular sites to the plasma membrane in response to insulin. The insulin-regulatable transporter resides in a unique vesicle that comprises 3% or less of the low density microsomes of fat cells and has a limited protein composition that does not include the bulk of another translocatable protein, the insulin-like growth factor II receptor. Immunoprecipitation with 1F8 of microsomal glucose transporters photoaffinity labeled with [3H]cytochalasin B brings down 90% of the label. Similarly, immunoprecipitation with 1F8 of glucose transporters from insulin-stimulated plasma membranes photolabeled with 3-[125I]iodo-4-azidophenethylamido-7-O-succinyldeacetyl-f ors kolin, another transporter-selective reagent, results in 75% of the labeled transporter localized in the immunoprecipitate. Thus, insulin action involves the combined effect of translocation from at least two vesicle pools each containing different glucose transporters. The 1F8-reactive transporter comprises the majority of the total transporter pool that is responsible for the insulin-induced increase in glucose transporter number.
我们最近描述了一种单克隆抗体（1F8），它能识别脂肪和肌肉特有的一种葡萄糖转运蛋白形式（詹姆斯，D.E.，布朗，R.，纳瓦罗，J.，和皮尔希，P.F.（1988年）《自然》333卷，183 - 185页），这些组织通过显著增加葡萄糖摄取对胰岛素产生急性反应。在此，我们报告大鼠脂肪细胞拥有两种免疫上不同的葡萄糖转运蛋白：一种被1F8识别，另一种与针对人红细胞葡萄糖转运蛋白产生的抗体发生反应。免疫吸附实验表明，这些葡萄糖转运蛋白存在于不同的囊泡群体中，并且两种转运蛋白异构体都会响应胰岛素从细胞内位点转运到质膜。胰岛素可调节的转运蛋白存在于一种独特的囊泡中，这种囊泡占脂肪细胞低密度微粒体的3%或更少，并且其蛋白质组成有限，不包括另一种可转运蛋白——胰岛素样生长因子II受体的大部分。用[3H]细胞松弛素B进行光亲和标记的微粒体葡萄糖转运蛋白与1F8进行免疫沉淀，可沉淀出90%的标记物。同样，用另一种转运蛋白选择性试剂3 - [125I]碘 - 4 - 叠氮苯乙酰胺 - 7 - O - 琥珀酰去乙酰佛司可林对胰岛素刺激的质膜上的葡萄糖转运蛋白进行光标记后，与1F8进行免疫沉淀，结果75%的标记转运蛋白定位于免疫沉淀物中。因此，胰岛素作用涉及至少两个各自含有不同葡萄糖转运蛋白的囊泡池转运的联合效应。1F8反应性转运蛋白占负责胰岛素诱导的葡萄糖转运蛋白数量增加的总转运蛋白池的大部分。
