8 5 0 ▁am ino ▁ac ids . ▁Part icular ▁sequences ▁inside ▁the ▁catal yt ic ▁domain ▁or ▁at ▁the ▁N ‒ ter minus ▁of ▁some ▁US P s ▁have ▁been ▁character ised ▁as ▁U BL ▁( U bi quit in ▁like ) ▁and ▁D US P ▁( domain ▁present ▁in ▁u bi quit in ‒ specific ▁prote ases ) ▁domains ▁respectively . ▁In ▁some ▁cases , ▁regarding ▁the ▁U BL ▁domains , ▁it ▁has ▁been ▁reported ▁to ▁have ▁a ▁catal ysis ▁en han cing ▁function ▁as ▁in ▁the ▁case ▁of ▁US P 7 . ▁In ▁addition , ▁a ▁so ‒ called ▁D U ▁domain ▁module ▁is ▁the ▁combination ▁of ▁a ▁D US P ▁domain ▁followed ▁by ▁a ▁U BL ▁domain ▁separated ▁by ▁a ▁linker ▁and ▁is ▁found ▁in ▁US P 1 1 ▁as ▁well ▁as ▁in ▁US P 1 5 ▁and ▁US P 4 . ▁ ▁US P 1 1 ▁is ▁ 9 6 3 aa ▁protein ▁with ▁a ▁M W ▁of ▁approximately ▁ 1 0 9 . 8 ▁k Da ▁and ▁a ▁p I ▁of ▁~ 5 . 2 8 ; ▁it ▁shares ▁significant ▁hom ology ▁with ▁US P 1 5 ▁and ▁along ▁with ▁US P 4 ▁forms ▁the ▁D U ▁sub family . ▁Nevertheless , ▁alignment ▁of ▁the ▁three ▁US P s ▁confir ms ▁that ▁US P 1 5 ▁and ▁US P 4 ▁are ▁the ▁closest ▁hom olog ues ▁with ▁the ▁identity ▁reaching ▁~ 7 3 ▁% ▁between ▁their ▁U BL 1 ▁domains ▁whereas ▁US P 1 1 ▁is ▁the