Methionyl-tRNA formyltransferase that formylates methionyl-tRNA in mitochondria and is crucial for translation initiation. (6S)-10-formyltetrahydrofolate + L-methionyl-tRNA(fMet) = (6S)-5,6,7,8-tetrahydrofolate + H(+) + N-formyl-L-methionyl-tRNA(fMet) Composed of an N- and a C-terminal domain. The N-terminal domain carries the tetrahydrofolate (THF)-binding site and the C-terminal domain is presumably involved in positioning the Met-tRNA substrate for the formylation reaction. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the Fmt family. Extended N-terminus. Extended N-terminus. Truncated N-terminus.