In many binder puzzles, the binder portion is mostly available for design. Some parts of the binder may be locked or held in place by constraints. Most of the segments in the binder are normally mutable. In some puzzles, the binding area is part of a larger protein, in which case much of the protein may be locked, with only certain segments mutable. The target in a binder puzzle is generally more or less fixed. Much of the target may be locked. It may be possible to wiggle the sidechains of part of the target, but generally the target's backbone has a fixed shape.