The Tim9-Tim10 complex is a hexameric mitochondrial intermembrane space (IMS) chaperone that can interact with imported proteins as they exit the TOM complex and keep them in an unfolded state. For β-barrel proteins destined for the outer mitochondrial membrane, the Tim9-Tim10 complex hands-off proteins to the SAM complex. TIM9-TIM10 complex also acts as a chaperone for a subset of multipass transmembrane proteins destined for insertion into the inner membrane by the TIM22 complex. (Adapted from PMID:11875042 and PMID:18706423.)