Multiple protein sequence alignment of the E2 family members in cotton. G. hirsutum-1 to 4 correspond to the protein sequences [GenBank:AAL99220.1, GenBank:AAL99222.1, GenBank:AAL99221.1 and GenBank:AAL99219.1] . G. raimondii, G. thurberi, G. arboreum and GhGDRP85 [GenBank:AAL99225.1, GenBank:AAL99224.1, GenBank:AAL99223.1 and GenBank:EU373075.1], respectively. The cysteine residue required for ubiquitin binding is indicated by an asterisk. The alignment was performed using ClustalW  and identity/similarity shading was performed with BoxShade 3.21.