Group III intron
Group III intron is a class of introns found in mRNA genes of chloroplasts in euglenid protists. They have a conventional group II-type dVI with a bulged adenosine, a streamlined dI, no dII-dV, and a relaxed splice site consensus. Splicing is done with two transesterification reactions with a dVI bulged adenosine as initiating nucleophile; the intron is excised as a lariat. Not much is known about how they work, although an isolated chloroplast transformation system has been constructed. Discovery and identification. In 1984, Montandon and Stutz reported examples of a novel type of introns in  Euglena chloroplast. In 1989, David A. Christopher and Richard B. Hallick found a few more examples and proposed the name "Group III introns" to identify this new class with the following characteristics: In 1994, discovery of a group III intron with a length of one order of magnitude longer indicated that length alone is not the determinant of splicing in Group III introns. Splicing of group III introns occurs through lariat and circular RNA formation. Similarities between group III and nuclear introns include conserved 5' boundary sequences, lariat formation, lack of internal structure, and ability to use alternate splice boundaries