tRNA-isoleucine-tryptophan Composite Gene
  Transfer-RNA genes in archaea often have introns intervening between exon sequences. The structural motif at the boundary between exon and intron is the bulge-helix-bulge. Computational investigations of these boundary structures in H. marismortui lead us to propose that tRNA-isoleucine and tRNA-tryptophan genes are co-located. Precise insilico identification of the splice-sites on the bulges at the exon-intron boundaries conduce us to infer that a single intron-containing composite tRNA-gene can give rise to more than one gene produc. 
Zhumur Ghosh, Jayprokas Chakrabarti, Bibekanand Mallick, Smarajit Das,   Satyabrata Sahoo and Harmeet Singh Sethi