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Mitochondrial protein import requires multiple energy sources, types of signals,

ID: 165396 • Letter: M

Question

Mitochondrial protein import requires multiple energy sources, types of signals, and pore complexes. Consider the require- ments needed for import and proper processing of four different types of mitochondrial proteins: 1) a matrix enzyme (alcohol dehydrogenase), 2) an inter-membrane space protein (cytochrome c), 3) an inner membrane transmembrane protein (cytochrome oxidase Va), and 4) an outer membrane transmembrane protein (porin). Indicate which components are required for proper location and maturation of each of these proteins Use a “+” to indicate required and “-” not required.

TIM complex Matrix chaperones nner membrane space protease cytosolic chaperones alcohol dehydrogenase cytochrome c cytochrome oxidase Va porin

Explanation / Answer

Cytochrome c

TIM Complex Matrix Chaperons Inner Membrane space protease Cytosolic chaperones Alcohol dehydrogenase + + + +

Cytochrome c

_ _ _ + Cytochrome oxydase Va + _ + + Porin _ _ _ +