The translocon of the mitochondrial outer membrane is functionally equivalent to ER translocon. However, why is...

The translocon of the mitochondrial outer membrane is functionally equivalent to ER translocon. However, why is Hsc70 needed for mitochondrial import but not for import into the ER?

Expert Solution

Transport of proteins into ER lumen is co-translational translocation in which protein synthesis is arrested by SRP and doesn't resume until the entire complex is delivered to the ER. So protein reaches the ER in unfolded state. If protein get folded it would not be able to enter in ER lumen.

On other hand proteins that are synthesized in cytosol are transported after the synthesis is complete. Here Hsc70 which is a chaperone prevents the folding of the protein. This is required because a folded protein can not enter into the translocon of mitochondria. So in ER there is no need of Hsc70 because proteins are synthesized in ER lumen. But for mitochondrial proteins Hsc1 is required to maintain them unfolded state until the protein is not translocated to mitochondria.

gladiator answered 2 years ago

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