Location alters tRNA identity: Trypanosoma brucei's cytosolic elongator tRNA~Met is both the initiator and elongator in mitochondria

摘要

As a rule, protein synthesis is initiated with methionine or formyl methio- nine from the first AUG codon in an ORF and that AUG is recognized by an initiator tRNA~Met-i. Internal AUG codons are then translated by a second tRNA, the elonga- tor tRNA~Met-e (1). In eubacteria, mito- chondria, and chloroplasts, the tRNA~Met-i is charged with methionine, and subse- quently the methionine is formylated by a methionyl-tRNA transformylase, whereas in the eukaryotic cytosol and archea, the methionine on the tRNA~Met-i is not formy- lated (2).