Hedley M L, Amrein H, Maniatis T
Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA.
Proc Natl Acad Sci U S A. 1995 Dec 5;92(25):11524-8. doi: 10.1073/pnas.92.25.11524.
We have identified an amino acid sequence in the Drosophila Transformer (Tra) protein that is capable of directing a heterologous protein to nuclear speckles, regions of the nucleus previously shown to contain high concentrations of spliceosomal small nuclear RNAs and splicing factors. This sequence contains a nucleoplasmin-like bipartite nuclear localization signal (NLS) and a repeating arginine/serine (RS) dipeptide sequence adjacent to a short stretch of basic amino acids. Sequence comparisons from a number of other splicing factors that colocalize to nuclear speckles reveal the presence of one or more copies of this motif. We propose a two-step subnuclear localization mechanism for splicing factors. The first step is transport across the nuclear envelope via the nucleoplasmin-like NLS, while the second step is association with components in the speckled domain via the RS dipeptide sequence.
我们在果蝇性别转换蛋白（Tra）中鉴定出一段氨基酸序列，该序列能够将异源蛋白导向核斑点，核斑点是细胞核中先前已证明含有高浓度剪接体小核RNA和剪接因子的区域。该序列包含一个核质蛋白样双分型核定位信号（NLS）以及一个与一小段碱性氨基酸相邻的重复精氨酸/丝氨酸（RS）二肽序列。对许多共定位于核斑点的其他剪接因子进行序列比较，发现了该基序的一个或多个拷贝。我们提出了一种剪接因子的两步亚核定位机制。第一步是通过核质蛋白样NLS穿过核膜，而第二步是通过RS二肽序列与斑点区域中的成分结合。
