ID #2437

In one of the slides from lecture 25, there is a picture of ATP being used near the mitochondrial Hsp70. (It is the slide with the chaperonin in it.) What is this ATP being used for? Is that representing the ATP that is used to fold proteins because it seems like it's in a different spot than it would if that's what it is for?

Once the positively charged mitochondrial presequence is fed through Tom and into the intermembrane space, it wants to reach the more negatively charged matrix. So, no energy is required to feed the presequence through into Tim. But after that, MPP cleaves off the presequence and the rest of the unfolded polypeptide still needs to get through Tim. Energy (in the form of ATP) is required to pull the rest of the unfolded polypeptide through Tim and into the matrix. 
As you noted, this is in addition to the ATP used to open up the chaperonin and allow some proteins to fold inside. 

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