The synthesis of the mitochondrial inner membrane 32 000 M r protein from rat brown adipose tissue was examined. Polysomes from the tissue were translated in a reticulocyte lysate protein-synthesizing system and newly-synthesized protein isolated with a monospecific antibody against the 32 000 M r protein. The newly-synthesized protein had the same relative molecular mass as the mature protein. It was taken up by mitochondria isolated from Chinese hamster ovary cells into a form resistant to trypsin.
