NOTE: Because many players have had trouble playing this puzzle, the puzzle has been made worth zero points, and it will not contribute to player rankings. However, this puzzle is still of unique scientific interest, and we encourage players to work on it if they are able!
This is a big one! This electron density puzzle features two proteins: the first is a large well-ordered helical protein that is mostly frozen in place. This binder protein has two flexible loops that bind a second, mostly disordered, substrate protein. The substrate protein is provided here as an extended chain, and is completely flexible. We know that the substrate protein is bound to the binder protein somewhere in this crystal structure. But it seems that the substrate is able to adopt several different shapes, making the electron density very difficult to interpret. We’re asking Foldit players to help us find the ways that the substrate protein can bind to the binder protein! Fold up the extended chain and dock it next to the flexible loops of the binder to improve your score!