A recent article in Nature explored the means by which certain proteins called chaperonins work. Chaperonins are proteins which help other proteins fold correctly. Specifically, they provide a "cage" in which the target protein can fold without interference. Artificially growing or shrinking the size of the cage can make certain proteins fold more quickly or slowly, but the overall size of the cage seems to be optimal given the number of proteins which this chaperonin interacts with.

Because the cell is so crowded with large molecules, it is energetically favorable for newly transcribed proteins to fold compactly, reducing the volume they occupy. If it weren't for chaperonins, this tendency would cause partially complete amino acid chains to bind with each other (there are many of these chains in close proximity because mRNA is transcribed by many ribosomes at once).

The upshot is that chaperonins use the energetic effects of crowding to stimulate folding while at the same time eliminating the negative effects of crowding - promiscuous binding to anything in the area. This is a neat trick. In the final paragraph of the article, the author (who, of course, credits natural selection with chaperonin design) even exhorts human designers to follow the example of chaperonins:

It is a testament to the ingenuity of natural selection that the chaperonin cage not only combats aggregation caused by crowding outside the cage but also uses crowding to accelerate protein folding inside the cage. Nanoengineers trying to improve the yield of therapeutic proteins could profit from studying the tricks of the chaperonin nanocage.