PDB; 1BCP; X-ray; 2.70 A; A/G=35-269.
PDB; 1PRT; X-ray; 2.90 A; A/G=36-269.
PDB; 1PTO; X-ray; 3.50 A; A/G=26-269.
PDB; 6RO0; X-ray; 2.13 A; A/G=1-269.