Figure 4.

A cartoon of how fly casting increases folding speed. At an approach distance R_cm, the partially folded ensemble is already able to form a few initial contacts to the binding site, while the folded structure remains out of range because of the smaller fluctuations in the folded state. Although these initial contacts are weak, they allow the protein to “reel” itself into the operator, completing folding and binding simultaneously. The increased capture radius allows the unfolded protein to find its specific binding site faster.