Possible mechanisms of MFP regulation. MFPs perform their function in the cell either by applying their enzymatic activity or simply through their structural function, for instance, as scaffold proteins (a). Furthermore, MFPs often associate with alternative proteins, which trap them in individual protein complexes to perform specific roles (b). Finally, MFPs can be regulated by modifications or molecular interactions that affect their conformation. Conformational changes may block one of their activity (e.g., the enzymatic activity) or block the formation of one of the complexes. In this way the conformational change may promote one of the pathways over the other (c).