File:Toxins-09-00300-g001.gif

English: CyaA is a 1706 residue-long polypeptide that consists of an N-terminal AC enzyme domain (~400 residues) and a C-terminal Hly moiety (~1300 residues) that are linked together with a ~100 residue-long segment (residues 400 to 500). The Hly portion of CyaA itself harbors several functional subdomains: (i) a hydrophobic pore-forming domain (residues 500 to 700); (ii) an activation domain (residues 800 and 1000), where the posttranslational acylation at two lysine residues (K860 and K983) occurs; (iii) a typical calcium-binding RTX domain with the nonapeptide repeats binding calcium ions and with the CD11b/CD18-binding segment (residues 1166–1287); and (iv) a C-terminal secretion signal.