Cellular cofactors involved in transport of mRNAs of complex retroviruses and hepatitis B virus

人CRM 1（human CRM 1，hCRM 1）是输出蛋白家族的成员，具有作为富含亮氨酸的内斯受体和支持HTLV-1雷克斯和蛋白质多聚化的双重功能。为了研究Rex-CRM 1相互作用和雷克斯多聚化的机制，我们专注于大鼠细胞中受损的雷克斯功能。我们克隆了大鼠CRM 1（rCRM 1）的cDNA，并与hCRM 1比较了雷克斯（Rex）的功能。我们的研究结果表明，rCRM 1不支持雷克斯功能有效地，因为一个穷人的能力，以诱导雷克斯多聚化，虽然它强烈结合到雷克斯内斯.Detailed比较人类和大鼠CRM 1序列，然后通过构建嵌合体和突变CRM 1蛋白质，使我们能够确定的氨基酸结合到雷克斯内斯和雷克斯多聚化的关键。这些结果表明，CRM 1支持雷克斯多聚化的能力与有效的内斯结合是分离的，这意味着CRM 1与雷克斯之间的相互作用比通过雷克斯的内斯区域的简单结合更高级，我们还发现CRM 1支持HIV Rev蛋白的多聚化。Rev蛋白的羧基端稳定了内斯区与CRM 1的相互作用，从而导致Rev蛋白的有效多聚化。

Human CRM1 (hCRM1), a member of exportin family, has dual functions as a receptor for leucine-rich NES and in supporting the multimerization of HTLV-1 Rex and protein. To investigate the mechanism of Rex-CRM1 interaction and multimerization of Rex, we focused on impaired Rex function in rat cells. We cloned a cDNA encoding rat CRM1 (rCRM1) and compared with hCRM1 in Rex function. Our results indicate that rCRM1 does not support Rex function efficiently because of a poor ability to induce Rex multimerization, although it binds strongly to the Rex NES.Detailed comparison of human and rat CRM1 sequences, followed by construction of chimera and mutant CRM1 proteins allowed us to identify the amino acids critical for binding to the Rex NES and for Rex multimerization. These results suggested that the capacity of CRM1 to support Rex multimerization is separable from efficient NES binding, implying a higher order interaction between CRM1 and Rex than simple association via the NES region of Rex.We also found CRM1 supports multimerization of HIV Rev protein. Carboxy terminal of Rev protein stabilizes the interaction of NES region with CRM1, consequently leading to efficient multimerization of Rev proteins.