The enzyme is composed of two subunits in green plants (including Chlorophyceae, Marchantimorpha, Bryopsida, Pinaceae, monocotyledons, and eudicots), species of fungi, Glaucophytes, Chlamydomonas, and prokaryotes.
Ampicillin, like other β-lactam antibiotics, not only blocks the division of bacteria, but also the division of chloroplasts of the glaucophytes (called cyanelles) and chloroplasts of the moss Physcomitrella patens, a bryophyte.