| D | Formyl_trans_N | e4ltrD1 | 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 | e4ltrC1 | 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 | e4ltrB1 | 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) |
| A | Formyl_trans_N | e4ltrA1 | 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) |