Author response image 3. Schematic of mitochondrial import steps involve Hsp70 and Tom70.

In yeast, Hsp70 binds and maintains nascent mitochondrial proteins in unfolded states before transferring them to Tom70 for import (Young et al., 2003). Tim23, the key subunits of the inner membrane translocase TIM complex, acts downstream of TOM complex (including the subunit Tom70) in mitochondrial import. Tim23 inactivation blocks the mitochondrial import of nascent mitochondrial proteins, which stay on the surface of mitochondria and associate with upstream factors, such as Tom70.