Metabolism of proline takes place in:
The catabolism of proline takes place in mitochodria. Since proline does not paicipate in transamination, the nitrogen of this imino acid is retained throughout its oxidation to 1-pyrolline-5-carboxylate, ring opening to glutamate--semialdehyde, and oxidation to glutamate, and is only removed during transamination of glutamate to a-ketoglutarate Ref: Harper 28th edition, chapter 29.
Mitochondria
Cell membrane
Ribosome
All of the above