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

我们的细胞由几种成分组成，包括我们在称为细胞质的细胞区室中组装的蛋白质。从那里，这些新蛋白质被靶向细胞内的不同位置以执行其任务。其中一个位置是细胞核，它包含我们的遗传信息，并由双层信封分隔。对于可溶性蛋白质，已经鉴定了多种信号，并且核输入由穿过核膜的小孔和涉及称为输入蛋白和Ran的蛋白质等的复杂机制介导。相比之下，膜蛋白的细胞核通过一个知之甚少的途径到达该隔室暗示一个松散定义的靶向信号。表征这种机制是重要的，因为这些蛋白质的不适当的核靶向会妨碍它们的功能。

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.