Metabolism of proline takes place in:
Mitochondria
Cell membrane
Ribosome
All of the above
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.