TIM22 pathway, membrane protein

The two complexes that import cytosolic proteins through the mitochondrial inner membrane, TIM22 and TIM23 split the import pathways of hydrophobic inner membrane proteins from that of presequence-containing preproteins (Fig. 1). 

Three different assembly pathways have been suggested for the imported inner membrane proteins. All three utilize the so-called TOM complex for translocation through the outer membrane. Two of the pathways further make use of the same TIM23 complex in the inner membrane that also handles soluble matrix proteins the third involves both a distinct set of chaperones in the intermembrane space as well as a distinct inner membrane insertion machinery, the TIM22 complex. 

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