Künzler M, Hurt E C
Biochemie-Zentrum Heidelberg, Ruprecht-Karls-Universität, Germany.
FEBS Lett. 1998 Aug 21;433(3):185-90. doi: 10.1016/s0014-5793(98)00892-8.
CSE1 is essential for yeast cell viability and has been implicated in chromosome segregation. Based on its sequence similarity, Cse1p has been grouped into the family of importin beta-like nucleocytoplasmic transport receptors with highest homology to the recently identified human nuclear export receptor for importin alpha, CAS. We demonstrate here that Cse1p physically interacts with yeast Ran and yeast importin alpha (Srp1p) in the yeast two-hybrid system and that recombinant Cse1p, Srp1p and Ran-GTP form a trimeric complex in vitro. Re-export of Srp1p from the nucleus into the cytoplasm and nuclear uptake of a reporter protein containing a classical NLS are inhibited in a cse1 mutant strain. These findings suggest that Cse1p is the exportin of importin alpha in yeast.
CSE1对酵母细胞的生存能力至关重要，并且与染色体分离有关。基于其序列相似性，Cse1p已被归入类importin β核质转运受体家族，与最近鉴定出的importin α的人类核输出受体CAS具有最高的同源性。我们在此证明，在酵母双杂交系统中，Cse1p与酵母Ran和酵母importin α（Srp1p）发生物理相互作用，并且重组Cse1p、Srp1p和Ran-GTP在体外形成三聚体复合物。在cse1突变菌株中，Srp1p从细胞核重新输出到细胞质以及含有经典核定位信号的报告蛋白的核摄取均受到抑制。这些发现表明Cse1p是酵母中importin α的输出蛋白。
