Posted on by Dr. Francis Collins
Credit: The Rockefeller University, New York
Sixty years ago, folk singer Pete Seeger recorded a song about helping those in need. The song starts like this: “Oh, had I a golden thread/And a needle so fine/I’d weave a magic strand/Of rainbow design.” In this brief animation, it seems like a golden thread and a needle are fast at work. But this rainbow design helps to answer a longstanding need for cell biologists: a comprehensive model of the thousands of pores embedded in the double-membrane barrier, or nuclear envelope, that divides the nucleus and its DNA from the rest of the cell.
These channels, called nuclear pore complexes (NPCs), are essential for life, tightly controlling which large macromolecules get in or out of the nucleus. Such activities include allowing vital proteins to enter the nucleus, blocking out harmful viruses, and shuttling messenger RNAs from the nucleus to the cytoplasm, where they are translated into proteins.
This computer simulation starts with an overhead view of the fully formed NPC structure. From this angle, the pore membrane (gray) appears to be at the base and is embroidered in four rings that are the channel’s main architectural support beams. There’s the cytoplasmic outer ring (yellow), the inner rings (purple, blue), the membrane ring (brown), and the nucleoplasmic outer ring (yellow). Each color represents different protein complexes, not rings per se, and the hole in the middle is the central channel through which molecules are transported. Filling the hole is a selective gating mechanism made of disordered protein (anchored to green) that helps to get the right molecules in and out.