Crystal structure of ACE2. The peptidase domain (PD) is in green, whereas the collectrin homology domain is enclosed in the light cyan square. The active zinc ion is showed enclosed in a red circle, whereas the glycosylation moieties are showed as cyan cubes and denoted by dashed arrows. The structures have been drawn from PDB 1R42 (Towler et al., 2004) by Mol on the PDB website.