97' and Klabunde et al. However their distribution is sporadic in species and in hosts. Some species have no inteins, some just one and Methanococcus jannaschii has nineteen. For species with completely sequenced genomes like E.coli , M.jannaschii and S. cerevisiae we know the total number of inteins in the strain sequenced. For other species we can only estimate their number.
Intein distribution seems most varied in archaea.
This table compares the inteins found in archaea with fully sequenced genomes. One major group of organisms where inteins are not known in is multicellular eucaryotes, both metazoa and plants. The multicellular red alga Porphyra does contain an intein but in its chloroplast genome. The reasons for this absence are not clear. Inteins may yet be found in these organisms and only turn out to be scarcer or perhaps difficult to detect.