>2c21B (B:) observed residues (from ATOM records)
srrmlhtmirvgdldrsikfyterlgmkvlrkwdvpedkytlvflgygpemsstvlelty
nygvtsykhdeayghiaigvedvkelvadmrkhdvpidyedesgfmafvvdpdgyyiell
nektmmekaeadmkeqgta