Physiological significance of the two isoforms of initiator tRNAs in .

Unlabelled: possesses four initiator tRNA (i-tRNA) genes, three of which are present together as and the fourth one as . In B, all four genes ( and ) encode i-tRNA, in which the G at position 46 is modified to mG46 by TrmB (mG methyltransferase). However, in K, because of a single-nucleotide polymorphism, encodes a variant, i-tRNA, having an A in place of mG46.