Aratani Satoko, Oishi Takayuki, Fujita Hidetoshi, Nakazawa Minako, Fujii Ryouji, Imamoto Naoko, Yoneda Yoshihiro, Fukamizu Akiyoshi, Nakajima Toshihiro
Department of Genome Science, Institute of Medical Science, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan.
Biochem Biophys Res Commun. 2006 Feb 3;340(1):125-33. doi: 10.1016/j.bbrc.2005.11.161.
RNA helicase A (RHA), an ATPase/helicase, regulates the gene expression at various steps including transcriptional activation and RNA processing. RHA is known to shuttle between the nucleus and cytoplasm. We identified the nuclear localization signal (NLS) of RHA and analyzed the nuclear import mechanisms. The NLS of RHA (RHA-NLS) consisting of 19 amino acid residues is highly conserved through species and does not have the consensus classical NLS. In vitro nuclear import assays revealed that the nuclear import of RHA was Ran-dependent and mediated with the classical importin-alpha/beta-dependent pathway. The binding assay indicated that the basic residues in RHA-NLS were used for interaction with importin-alpha. Furthermore, the nuclear import of RHA-NLS was supported by importin-alpha1 and preferentially importin-alpha3. Our results indicate that the nuclear import of RHA is mediated by the importin-alpha3/importin-beta-dependent pathway and suggest that the specificity for importin may regulate the functions of cargo proteins.
RNA解旋酶A（RHA）是一种ATP酶/解旋酶，在包括转录激活和RNA加工在内的多个步骤中调节基因表达。已知RHA穿梭于细胞核和细胞质之间。我们鉴定了RHA的核定位信号（NLS）并分析了核输入机制。由19个氨基酸残基组成的RHA的NLS（RHA-NLS）在物种间高度保守，且不具有经典NLS的共有序列。体外核输入实验表明，RHA的核输入是Ran依赖性的，并通过经典的输入蛋白α/β依赖性途径介导。结合实验表明，RHA-NLS中的碱性残基用于与输入蛋白α相互作用。此外，RHA-NLS的核输入由输入蛋白α1支持，且优先由输入蛋白α3支持。我们的结果表明，RHA的核输入由输入蛋白α3/输入蛋白β依赖性途径介导，并表明对输入蛋白的特异性可能调节货物蛋白的功能。
