Leaderless mRNAs in prokaryotes may actually be initiated on 70S ribosomes rather than on the 30S subunit (Moll et al. 2004; Udagawa et al. 2004).The fact that mitochondrial mRNAs are leaderless raises the question of whether information exists at or near the 5??? ends of these RNAs that enables them to be efficiently recognized by the mitochondrial translational machinery.