Promotes mitochondrial protein synthesis. May act as a fidelity factor of the translation reaction, by catalyzing a one-codon backward translocation of tRNAs on improperly translocated ribosomes. Binds to mitochondrial ribosomes in a GTP-dependent manner. GTP + H2O = GDP + H(+) + phosphate Belongs to the TRAFAC class translation factor GTPase superfamily. Classic translation factor GTPase family. LepA subfamily. Extended N-terminus.