Question

Where would you find the precursor of a mitochondrial matrix protein in the following types of mitochondrial mutants?

-	A mutation in the Tom22 signal receptor
-	A mutation in the Tom70 signal receptor
-	A mutation in the matrix Hsp70
-	A mutation in the matrix signal peptidase
-	A mutation in the Tim44 signal receptor

A.	Cytosol
B.	Matrix
C.	Intermembrane space
D.	Outer membrane

Answer 1

mutation in TOM22 will cause the precursor mitochondrial protein to be in cytosol. because functional TOM22 is a binding site for amino terminal.

Mutation in TOM70 signal receptor- cytosol

mutation in the matrix Hsp70- cytosol.

mutation in signal peptidase- matrix. it will still be attached with the innermembrane by the n-terminus.

mutation in the Tim44 signal receptor- Intermembrane space. because functional Tim44 translocates precursor proteins through inner membrane.