Taura T, Krebber H, Silver P A
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School and The Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 1998 Jun 23;95(13):7427-32. doi: 10.1073/pnas.95.13.7427.
Yeast cells mutated in YRB2, which encodes a nuclear protein with similarity to other Ran-binding proteins, fail to export nuclear export signal (NES)-containing proteins including HIV Rev out of the nucleus. Unlike Xpo1p/Crm1p/exportin, an NES receptor, Yrb2p does not shuttle between the nucleus and the cytoplasm but instead remains inside the nucleus. However, by both biochemical and genetic criteria, Yrb2p interacts with Xpo1p and not with other members of the importin/karyopherin beta superfamily. Moreover, the Yrb2p region containing nucleoporin-like FG repeats is important for NES-mediated protein export. Taken together, these data suggest that Yrb2p acts inside the nucleus to mediate the action of Xpo1p in at least one of several nuclear export pathways.
YRB2发生突变的酵母细胞无法将包括HIV Rev在内的含有核输出信号（NES）的蛋白质输出细胞核，YRB2编码一种与其他Ran结合蛋白相似的核蛋白。与NES受体Xpo1p/Crm1p/输出蛋白不同，Yrb2p不会在细胞核和细胞质之间穿梭，而是留在细胞核内。然而，根据生化和遗传学标准，Yrb2p与Xpo1p相互作用，而不与输入蛋白/核转运蛋白β超家族的其他成员相互作用。此外，含有核孔蛋白样FG重复序列的Yrb2p区域对NES介导的蛋白质输出很重要。综上所述，这些数据表明Yrb2p在细胞核内发挥作用，至少在几种核输出途径之一中介导Xpo1p的作用。
