| Gene | Description | Domains |
|---|---|---|
| Spis_XP_022792135_1 | ubiquitin like modifier activating enzyme 1 | E1_4HB, E1_FCCH, E1_UFD, ThiF, UBA_e1_thiolCys |
| Spis_XP_022795514_1 | ubiquitin like modifier activating enzyme 6 | E1_4HB, E1_FCCH, E1_UFD, ThiF, UBA_e1_thiolCys |
| Spis_XP_022795976_1 | ubiquitin like modifier activating enzyme 2 | ThiF, UAE_UbL, UBA_e1_thiolCys |