Family 15 contains the plant MTs, which in 2002 have been further classified by Cobbet and Goldsbrough into 4 Types (1, 2, 3 and 4) depending on the distribution of their Cys residues and a Cys-devoid regions (called spacers) characteristic of plant MTs.
Familija 15 sadrži biljne metalotioneine, koje su 2002. bili dalje klasifikovani Kobet i Goldsbra u 4 tipa (1, 2, 3 i 4) u zavisnosti od distribucije njihovih cisteinskih ostataka i regiona u kojima nema cisteina (zvanih razmaknice), koji su karakteristični za biljne metalotioneine.