Molecular insights into the targeting of proteins to the inner nuclear membrane

我们的细胞由几种成分组成，包括我们在一个叫做细胞质的细胞隔间内组装的蛋白质。从那里，这些新的蛋白质被定位到细胞内的不同位置来执行它们的任务。其中一个位置是细胞核，它包含我们的遗传信息，由双层包膜分隔。对于可溶性蛋白，已经确定了多种信号，核进口是由穿过核包膜的小孔和一个复杂的机制介导的，其中包括称为进口蛋白和Ran的蛋白质。相比之下，前往细胞核的膜蛋白通过一种鲜为人知的途径到达该隔室，这意味着一个定义松散的靶向信号。表征这种机制是很重要的，因为不适当的核靶向这些蛋白质会阻碍它们的功能。

Our cells are made up of several constituents, including proteins that we assemble inside a cellular compartment called cytoplasm. From there, these new proteins are targeted to various locations within the cell to perform their tasks. One of those locations is the nucleus, which contains our genetic information and is delimited by a double layered envelope. For soluble proteins, a variety of signals have been identified and nuclear import is mediated by small pores traversing the nuclear envelopes and a complex machinery involving, among others, proteins called importins and Ran. In contrast, membrane proteins destined for the nucleus reach that compartment by a poorly understood route implicating a loosely defined targeting signal. Characterizing this machinery is important since improper nuclear targeting of these proteins would hamper their functions.