Movement of a karyophilic protein through the nuclear pores of oocytes.
Movement of a karyophilic protein through the nuclear pores of oocytes.
复制标题
核细胞通过卵母细胞的核孔的运动。
DOI：
10.1083/jcb.99.6.2216
复制
发表时间：
1984-12
影响因子：
7.8
通讯作者：
Schultz, N
中科院分区：
文献类型：
--
作者：
Feldherr, C M;Kallenbach, E;Schultz, N
最近的研究表明，在两栖动物卵母细胞中，大的亲核蛋白质可以通过核膜转运。考虑到这一点，进行本实验以鉴定包膜内发生转运的特定位点，并确定分子大小是否是转运过程中的限制因素。采用以下实验程序：用核质蛋白（一种165，000-mol-wt的亲核蛋白，已知其通过包膜转运）包被直径大小从约20至170 A变化的胶体金颗粒。将包被的金颗粒显微注射到非洲爪蟾卵母细胞的细胞质中，15 min和1 h后固定细胞。然后用电子显微镜确定金的细胞内定位。结果发现，核质溶酶包被的颗粒容易进入细胞核。根据与包膜相关的颗粒的分布，我们得出结论，运输通过核孔发生。此外，存在于细胞核和细胞质中的金颗粒的尺寸分布没有显著差异，表明包膜不能区分直径范围为50至200 A（包括核质蛋白外壳的尺寸）的颗粒。包被有胰蛋白酶消化的核质蛋白（缺乏转运所需的多肽结构域）或外源性聚乙烯吡咯烷酮的胶体金在很大程度上被排除在细胞核之外，没有显示出转运的证据。
It has recently been shown that large karyophilic proteins are transported across the nuclear envelope in amphibian oocytes. In consideration of this, the present experiments were performed to identify the specific sites within the envelope through which transport occurs and determine if molecular size is a limiting factor in the transport process. The following experimental procedure was employed: Colloidal gold particles, varying in size from approximately 20 to 170 A in diameter were coated with nucleoplasmin, a 165,000-mol-wt karyophilic protein, which is known to be transported through the envelope. The coated gold particles were microinjected into the cytoplasm of Xenopus oocytes, and the cells were fixed 15 min and 1 h later. The intracellular localization of the gold was then determined with the electron microscope. It was found that nucleoplasmin-coated particles readily enter the nucleus. On the basis of the distribution of the particles associated with the envelope, we concluded that transport occurs through the nuclear pores. Furthermore, the size distributions of the gold particles present in the nucleus and cytoplasm were not significantly different, indicating that the envelope does not discriminate among particles with diameters ranging from 50 to 200 A (the dimensions including the nucleoplasmin coat). Colloidal gold coated with trypsin-digested nucleoplasmin (which lacks the polypeptide domain required for transport) or exogenous polyvinylpyrrolidone were largely excluded from the nucleus and showed no evidence of transport.