Clans represent the deepest diverging
gene clades in the CYP nomenclature. There are ten P450
clans among animals, but only four are present in the protostomes:
CYP2, CYP3, CYP4 and mitochondrial. The
general web repository for P450 nomenclature and
sequence data is http://drnelson.utmem.edu/
cytochromeP450.html.