Table 2.

Characteristics and distribution of Cys-GSTs.

Class	Origin	Typical catalytic motif	Average amino acid length	Oligomerization state
GSTB	Bacteria	GA12CS	210	Dimer
GSTO	Mammals, insects, fungi	35CPFA	250	Dimer
CLIC	Animals	35CPFS	250	Monomer Dimer Oligomer
GSTL	Terrestrial plants	40CPF/YA	230	Monomer
DHAR	Algae, terrestrial plants	20CPFC/S	220	Monomer
GHR	Some metazoan but animals, algae, terrestrial plants, fungi, cyanobacteria, bacteria, archaea	50CPWA	330	Dimer
mPGES-2	Animals, protists, algae, terrestrial plants	110CPFC	310	Dimer
GSTH	Bryophyta, lycophyta	50CPF/YT	510	?
GSTI	Algae, bryophyta, lycophyta	120CPYC	490	?

The case of CLIC proteins is particular since it exists under both a monomeric soluble and an oligomeric transmembrane form. Moreover, the formation of an intramolecular disulfide bond promotes a structural transition that exposes a large hydrophobic surface changing the monomer into a non-covalent dimer (Littler et al., 2004).