| A | Ion_trans | e4ltoA1 | A: alpha bundles | X: Suppressor of Fused, C-terminal domain | H: RNA-binding domain, RBD | T: RNA-binding domain, RBD | F: Ion_trans | ECOD (develop294) |
| D | Formyl_trans_N | e4ltoD1 | A: alpha bundles | X: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | H: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | T: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | F: Formyl_trans_N | ECOD (develop294) |
| C | Formyl_trans_N | e4ltoC1 | A: alpha bundles | X: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | H: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | T: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | F: Formyl_trans_N | ECOD (develop294) |
| B | Formyl_trans_N | e4ltoB1 | A: alpha bundles | X: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | H: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | T: Fe-S cluster-binding domain in nickel-iron hydrogenase small subunit | F: Formyl_trans_N | ECOD (develop294) |