Cells have devised many structures for transporting molecular1 cargo2 across their protective borders, but the nuclear pore complex, with its flower-like, eight-fold symmetry, stands out. Monstrously3 large by cellular4 standards, as well as versatile5, this elaborate portal controls access to and exit from the headquarters of the cell, the nucleus6. In research published June 4 in Cell, Rockefeller University scientists have uncovered crucial steps in the dynamic dance that dilates8 and constricts9 the nuclear pore complex -- the latest advance in their ongoing10 efforts to tease apart the mechanism11 by which its central channel admits specific molecules12. Their work, based on quantitative13 biophysical data, has revealed that the nuclear pore complex is much more than the inert14 structure it was once thought to be.Prevailing15 wisdom cast the nuclear pore complex as a rigid16 conduit. Instead, we have found that it responds to the need for transport, opening and closing in an elegantly simple cycle, says study author Gunter Blobel, John D. Rockefeller Jr. Professor and head of the Laboratory of Cell Biology. Our most recent study reveals how proteins called transport factors, known to chaperone legitimate17 cargo through the nuclear pore complex, prompt the ring at the middle of the central channel to dilate7.More than a billion years ago, certain cells gained an evolutionary18 advantage by surrounding their DNA19 in a protective membrane20, creating the nucleus. However, this innovation created a problem: How to move molecules, in some cases very large ones, in and out. The nuclear pore complex was one solution, first described at Rockefeller over 50 years ago by Michael Watson, a postdoc in the Palade-Porter Laboratory. Years later, Blobels lab identified the first of the proteins that act as the complexs building blocks: nucleoporins. For some time, it has been assumed that unstructured portions of some nucleoporin molecules guarded the complexs rigid central channel by creating a sort of gel-like barrier.
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1 molecular adj.分子的；克分子的 参考例句： The research will provide direct insight into molecular mechanisms.这项研究将使人可以直接地知道分子的机理。 For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。
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