Greber U F, Gerace L
Department of Cell Biology, Scripps Research Institute, La Jolla, California 92037.
J Cell Biol. 1992 Jan;116(1):15-30. doi: 10.1083/jcb.116.1.15.
Gp210 is a major transmembrane glycoprotein associated with the nuclear pore complex that is suggested to be important for organizing pore complex architecture and assembly. A mouse monoclonal IgG directed against an epitope in the lumenal domain of rat gp210 was expressed in cultured rat cells by microinjection of mRNA prepared from a hybridoma cell line. The expressed IgG, which becomes assembled into a functional antibody in the lumen of the endoplasmic reticulum, bound to the nuclear envelope in vivo. Expression of anti-gp210 antibody in interphase cells specifically reduced approximately fourfold the mediated nuclear import of a microinjected nuclear protein (nucleoplasmin) coupled to gold particles. The antibody also significantly decreased nuclear influx of a 10-kD dextran by passive diffusion. This transport inhibition did not result from removal of pore complexes from nuclear membranes or from gross alterations in pore complex structure, as shown by EM and immunocytochemistry. A physiological consequence of this transport inhibition was inhibition of cell progression from G2 into M phase. Hence, binding of this antibody to the lumenal side of gp210 must have a transmembrane effect on the structure and functions of the pore complex. These data argue that gp210 is directly or indirectly connected to pore complex constituents involved in mediated import and passive diffusion.
Gp210是一种与核孔复合体相关的主要跨膜糖蛋白，被认为对组织孔复合体的结构和组装很重要。一种针对大鼠gp210腔内结构域表位的小鼠单克隆IgG，通过显微注射从杂交瘤细胞系制备的mRNA在培养的大鼠细胞中表达。表达的IgG在内质网腔内组装成功能性抗体，在体内与核膜结合。在间期细胞中表达抗gp210抗体可使显微注射的与金颗粒偶联的核蛋白（核质蛋白）介导的核输入特异性降低约四倍。该抗体还通过被动扩散显著降低了10-kD葡聚糖的核内流。如电子显微镜和免疫细胞化学所示，这种转运抑制并非由于从核膜上移除孔复合体或孔复合体结构的总体改变所致。这种转运抑制的生理后果是抑制细胞从G2期进入M期。因此，该抗体与gp210腔侧的结合必定对孔复合体的结构和功能产生跨膜效应。这些数据表明，gp210直接或间接与参与介导输入和被动扩散的孔复合体成分相连。
