Ubiquitin families were mainly identified through HMM search captured from UUCD. There are 21 subfamilies and 1,192 members in our database.

• E1
  • ThiF
• E2
  • UBC
• E3
  • E3 activity
    • HECT
    • RING
      • RING
      • U-box
    • N-recognin
      • UBR-box
      • N-domain
  • E3 adaptor
    • Cullin
    • F-box
    • SKP1
    • SOCS/VHL/BC-box
      • BC-box
    • BTB
    • 3-box
    • DDB1
    • DWD
• DUB
  • UCH
  • USP
  • OTU
  • Josephin
  • JAMM
  • ULP