In transposon copia-related retrovirus-like particles of Drosophila, a 5' half fragment produced by the cleavage of mature initiator methionine tRNA is used as the primer for minus-strand reverse transcription. This cleavage is called hyperprocessing. We have previously reported that the catalytic RNA subunit of RNase P catalyzes this hyperprocessing in vitro and that this cleavage is dependent on the occurrence of an altered conformation of the tRNA substrate. Here, we found that other mature tRNAs of Drosophila were also hyperprocessed by M1 RNA in vitro and that some of such tRNAs were probably alanine and histidine tRNAs. Here we report these two tRNAs can also adopt their alternative conformations very similar to that of initiator methionine tRNA.