The blank spots
They’re called “vaults”. They‘re in our cells, and in those of every plant, animal, and fungus. Like ribosomes, they’re atomically precise self-assembled structures made of protein and RNA, but they’re big and hollow, large enough to pack many ribosomes inside. They’re relatively simple and symmetric: A vault consists of two identical halves, each consisting almost entirely of 39 identical copies of a single, large protein (see figure). The vault structure was recently determined to near-atomic resolution, revealing enough detail to show how the proteins fold and fit together. Looking forward, this information could help protein engineers develop methodologies for designing large self-assembling structures.
Vaults are unusual in many ways, but what I find most surprising about them is this:
To this day, no one knows what they do.
No one knows what sleep is for, either, though at least part of its function seems to have something to do with memory.
What are some other notable blank spots?
Link thanks to shadesong.