Dabauvalle M C, Schulz B, Scheer U, Peters R
Institute of Zoology I, University of Würzburg, Federal Republic of Germany.
Exp Cell Res. 1988 Jan;174(1):291-6. doi: 10.1016/0014-4827(88)90163-2.
The lectin wheat germ agglutinin (WGA), which has been reported to inhibit nuclear protein uptake in vitro by isolated nuclei (Finlay et al. (1987) J. Cell Biol. 104, 189), also blocks, on microinjection into living cells, the migration of proteins into the cell nucleus. Radioactively labeled nuclear proteins were injected into the cytoplasm of Xenopus oocytes and their reentry into the nucleus was analyzed in the presence or absence of WGA by two-dimensional gel electrophoresis. In another set of experiments, fluorescently labeled nucleoplasmin was injected, alone or together with WGA, into the cytoplasm of rat hepatoma cells, and its nucleocytoplasmic distribution was studied by quantitative laser fluorescence microscopy. The results indicate that WGA inhibits the uptake of karyophilic proteins in general, independent of their sizes. Since the nucleocytoplasmic flux of a dextran with Mr 10,000 was not affected it can be excluded that WGA acts by a general blockade or constriction of the functional pore channel. At reduced WGA concentrations, the rate but not the final extent of nuclear protein accumulation was decreased. These findings support the concept that the O-glycosidically bound carbohydrates of certain nuclear pore complex proteins are exposed to the pore interior and that these regions are probably involved in nucleocytoplasmic translocation processes.
凝集素麦胚凝集素（WGA）据报道在体外能抑制分离细胞核摄取核蛋白（芬利等人，《细胞生物学杂志》，1987年，第104卷，第189页），在显微注射到活细胞中时，它也会阻断蛋白质向细胞核的迁移。将放射性标记的核蛋白注射到非洲爪蟾卵母细胞的细胞质中，并通过二维凝胶电泳分析在有或没有WGA的情况下它们重新进入细胞核的情况。在另一组实验中，将荧光标记的核质蛋白单独或与WGA一起注射到大鼠肝癌细胞的细胞质中，并通过定量激光荧光显微镜研究其核质分布。结果表明，WGA一般会抑制亲核蛋白的摄取，而与它们的大小无关。由于分子量为10,000的葡聚糖的核质通量不受影响，因此可以排除WGA通过对功能性孔道的普遍阻断或收缩起作用的可能性。在较低的WGA浓度下，核蛋白积累的速率降低，但最终程度未受影响。这些发现支持这样一种概念，即某些核孔复合体蛋白的O-糖苷键结合的碳水化合物暴露于孔内部，并且这些区域可能参与核质转运过程。
