Formylates methionyl-tRNA in mitochondria and the cytoplasm (PubMed:10781559, PubMed:30409808). Responsible for the formylation of the 8 N-terminally formylated (Nt-formylated) mitochondrial matrix proteins that are encoded by mitochondrial DNA (PubMed:10781559, PubMed:12549912). Nt-formylated proteins in the cytoplasm are strongly up-regulated in stationary phase or upon starvation for specific amino acids (His or Lys) and are targeted for degradation by a PSH1 E3 ubiquitin ligase-mediated fMet/N-end rule pathway. Increased Nt-formylation of cytosolic proteins appears to be important for adaptation to these stresses. Stationary phase-degraded Nt-formylated proteins include histone H3-like centromeric protein CSE4, Mediator complex subunit 3 (PGD1) and small ribosomal subunit protein uS8-A (RPS22A) (PubMed:30409808). (6S)-10-formyltetrahydrofolate + L-methionyl-tRNA(fMet) = (6S)-5,6,7,8-tetrahydrofolate + H(+) + N-formyl-L-methionyl-tRNA(fMet) kcat is 0.13 sec(-1) with L-methionyl-tRNA(fMet) as substrate. In exponentially growing cells, more than 97% of FMT1 is present in mitochondria. In stationary phase, about 35% of FMT1 becomes localized to the cytosol in a GCN2-dependent manner. Phosphorylated by GCN2 in response to nutrient deprivation. Phosphorylation mediates retention of FMT1 in the cytoplasm. Formylation of the initiator Met-tRNA is not essential for mitochondrial protein synthesis in S.cerevisiae. Present with 1070 molecules/cell in log phase SD medium. Belongs to the Fmt family.