A distinct class of endosome mediates clathrin-independent endocytosis to the Golgi complex
A distinct class of endosome mediates clathrin-independent endocytosis to the Golgi complex
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DOI：
10.1038/ncb787
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发表时间：
2002-05-01
影响因子：
21.3
通讯作者：
Nichols, BJ
中科院分区：
文献类型：
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作者：
Nichols, BJ
哺乳动物细胞内吞多种蛋白质和脂质，而不利用网格蛋白包被的小凹（1-5）。不依赖网格蛋白的内吞作用的详细分子机制尚不清楚。在抗洗涤剂膜组分（DRM）或脂筏中发现了该过程的几种标记物，包括鞘糖脂结合细菌毒素亚单位，如霍乱毒素B亚单位（CTX B）和糖基-磷脂酰-肌醇（GPI）锚定蛋白（2，3，5 -7）。高尔基复合体构成了这些标记物的一个主要细胞内目的地（2）。CTxB和GPI锚定蛋白的摄取可能涉及质膜（PM）中的小窝（caveolae）和小内陷（8-13）。然而，参与PM到高尔基体运输的中间细胞器的身份，以及小窝蛋白的功能，定义小窝的蛋白质组分（12，13），尚不清楚。本文表明，分子分配到DRM和内吞的网格蛋白独立的方式，积累在一个离散的人口的内涵体途中高尔基复合体。这些内体缺乏经典早期和再循环内体的标记，但确实含有小窝蛋白-1。小窝蛋白-1阳性内体是将小窝蛋白-1从高尔基体结合的货物中分选出来的位点，尽管小窝蛋白-1本身不太可能在PM到高尔基体的运输中具有直接功能。
Mammalian cells endocytose a variety of proteins and lipids without utilising clathrin-coated pits(1-5). Detailed molecular mechanisms for clathrin-independent endocytosis are unclear. Several markers for this process, including glycosphingolipid-binding bacterial toxin subunits such as cholera toxin B subunit ( CTxB), and glycosyl-phosphatidyl-inositol (GPI)-anchored proteins, are found in detergent-resistant membrane fractions (DRMs), or lipid rafts'(2,3,5-7). The Golgi complex constitutes one principal intracellular destination for these markers(2). Uptake of both CTxB and GPI-anchored proteins may involve caveolae, small invaginations in the plasma membrane (PM)(8-13). However, the identity of intermediate organelles involved in PM to Golgi trafficking, as well as the function of caveolins, defining protein components of caveolae(12,13), are unclear. This paper shows that molecules which partition into DRMs and are endocytosed in a clathrin-independent fashion, accumulate in a discrete population of endosomes en route to the Golgi complex. These endosomes are devoid of markers for classical early and recycling endosomes, but do contain caveolin-1. Caveolin-1-positive endosomes are sites for the sorting of caveolin-1 away from Golgi-bound cargoes, although caveolin-1 itself is unlikely to have a direct function in PM to Golgi transport.