Figure 3.
Potential ATP-dependent mechanisms of subunit exchange. A: An ATP-dependent post-translational modification of an IF tetramer (example illustrated, phosphorylation) induces its dissociation from ULF. Removal of the modification (here by the action of a phosphatase) allows the lateral association of tetramers into ULF. B: ATP-dependent binding of an IF tetramer to a chaperone facilitates its dissociation from a ULF and maintains the tetramer’s solubility. Release of the tetramer from the chaperone (for example via ATP hydrolysis) is necessary for the tetramer to laterally associate into ULF.