Three-dimensional visualization of coated vesicle formation in fibroblasts.
Three-dimensional visualization of coated vesicle formation in fibroblasts.
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DOI：
10.1083/jcb.84.3.560
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发表时间：
1980-03
期刊：
影响因子：
--
通讯作者：
Heuser J
中科院分区：
文献类型：
--
作者：
Heuser J
成纤维细胞显然通过受体介导的内吞作用的选择性机制摄取低密度脂蛋白（LDL），该机制涉及从质膜形成包被囊泡。然而，目前还不清楚包被囊泡如何收集LDL受体并从质膜上夹断。在本报告中，快速冷冻，深蚀刻，旋转复制方法已被应用于成纤维细胞，它显示了异常清晰的外套，出现在质膜下的受体介导的内吞作用开始。这些涂层似乎是7纳米链或支柱排列成30纳米多边形的多边形网络，其中大多数是六边形，但其中一些是5边和7边环。每个网络中五边形的比例随着质膜的涂覆区域从其平面构型（其中网络主要是六边形）起皱到其作为夹断涂覆囊泡的最急剧弯曲的条件而增加。最小囊泡（六边形和五边形的二十面体）周围的涂层似乎与从均质化脑中纯化的“空涂层”略有不同，后者是包含更多五边形而不是六边形的不对称篮子。在这种被毛转变中寻找结构中间体，可以对T. Kanaseki和K. Kadota's（1969. 42：202- 220）。最初的想法是，在这个编织物中，从六边形到五边形的内部重排可以“驱动”被包覆的囊泡的形成。典型六边形蜂窝中最值得注意的变化是在编织物的部分收缩和弯曲点处5边和7边多边形的焦点并置。这些似乎是在完全收缩成完全被六边形包围的单个五边形之前，这是包被囊泡周围最终球形篮的特征。
Fibroblasts apparently ingest low density lipoproteins (LDL) by a selective mechanism of receptor-mediated endocytosis involving the formation of coated vesicles from the plasma membrane. However, it is not known exactly how coated vesicles collect LDL receptors and pinch off from the plasma membrane. In this report, the quick-freeze, deep- etch, rotary-replication method has been applied to fibroblasts; it displays with unusual clarity the coats that appear under the plasma membrane at the start of receptor-mediated endocytosis. These coats appear to be polygonal networks of 7-nm strands or struts arranged into 30-nm polygons, most of which are hexagons but some of which are 5- and 7-sided rings. The proportion of pentagons in each network increases as the coated area of the plasma membrane puckers up from its planar configuration (where the network is mostly hexagons) to its most sharply curved condition as a pinched-off coated vesicle. Coats around the smallest vesicles (which are icosahedrons of hexagons and pentagons) appear only slightly different from "empty coats" purified from homogenized brain, which are less symmetrical baskets containing more pentagons than hexagons. A search for structural intermediates in this coat transformation allows a test of T. Kanaseki and K. Kadota's (1969. J. Cell Biol. 42:202--220.) original idea that an internal rearrangement in this basketwork from hexagons to pentagons could "power" coated vesicle formation. The most noteworthy variations in the typical hexagonal honeycomb are focal juxtapositions of 5- and 7-sided polygons at points of partial contraction and curvature in the basketwork. These appear to precede complete contraction into individual pentagons completely surrounded by hexagons, which is the pattern that characterizes the final spherical baskets around coated vesicles.