Simple kinetic relationships and nonspecific competition govern nuclear import rates in vivo.
Simple kinetic relationships and nonspecific competition govern nuclear import rates in vivo.
复制标题
简单的动力学关系和非特异性竞争控制体内核进口率。
DOI：
10.1083/jcb.200608141
复制
发表时间：
2006-11-20
影响因子：
7.8
通讯作者：
Rout, Michael P
中科院分区：
文献类型：
--
作者：
Timney, Benjamin L;Tetenbaum-Novatt, Jaclyn;Agate, Diana S;Williams, Rosemary;Zhang, Wenzhu;Chait, Brian T;Rout, Michael P
许多运往核进口的货物携带核粘附素(KAP)识别的核定位信号。我们提出了量化进口速率的方法，并在体内测量单个酵母细胞中的Kap和货物浓度，为进口动力学提供了新的见解。通过系统地操纵Kap和货物的数量、类型和亲和力，我们表明，体内的进口率只受Kap和它们的货物的浓度以及它们之间的亲和力的控制。这些速率符合进口过程的简单泵漏模型。令人意外的是，我们推断，进口的主要限制因素是Kaps和Cargo在压倒性的非特异性竞争背景下在细胞质中找到彼此的能力较差，而不是其他更明显的候选基因，如核孔复合体和Ran。很可能每一轮输入都被KAPS和核定位信号占据，当它们在细胞质中相互定位时，对其他细胞质蛋白进行采样。
Many cargoes destined for nuclear import carry nuclear localization signals that are recognized by karyopherins (Kaps). We present methods to quantitate import rates and measure Kap and cargo concentrations in single yeast cells in vivo, providing new insights into import kinetics. By systematically manipulating the amounts, types, and affinities of Kaps and cargos, we show that import rates in vivo are simply governed by the concentrations of Kaps and their cargo and the affinity between them. These rates fit to a straightforward pump–leak model for the import process. Unexpectedly, we deduced that the main limiting factor for import is the poor ability of Kaps and cargos to find each other in the cytoplasm in a background of overwhelming nonspecific competition, rather than other more obvious candidates such as the nuclear pore complex and Ran. It is likely that most of every import round is taken up by Kaps and nuclear localization signals sampling other cytoplasmic proteins as they locate each other in the cytoplasm.