I-CreI
I-CreI is a homing endonuclease whose gene was first discovered in the chloroplast genome of Chlamydomonas reinhardtii, a species of unicellular green algae. It is named for the facts that: it resides in an Intron; it was isolated from Clamydomonas reinhardtii; it was the first (I) such gene isolated from C. reinhardtii.