Fig. 6. Stages of DIC import into mitochondria. (I) Newly synthesized DIC is bound to chaperone proteins in the cytosol; (II) DIC then becomes bound to the import receptor Tom70; (III*) DIC is bound the Tim9-Tim10 complex in the intermembrane space [as defined by Zara et al. (Zara et al., 2001)]; (IV) insertion into the inner-membrane Tim22 complex; V, mature DIC. The carrier signature facilitates the transition from stage II to stage III* and is essential in the transport activity of the mature protein (large arrows). IM, inner membrane; IMS, intermembrane space; OM, outer membrane; R, receptor.