Pharmacotherapy for the management of achalasia: Current status, challenges and future directions

Figure 1 Structure of botulinum toxin A. The Cα backbone is represented as ribbons with the LC in cyan, the HN in dark blue and the HC in a green to yellow gradient highlighting the HCN and HCC subdomains. The HN belt is in red. H_N + H_C: 100 kDa heavy chain; H_N: 50 kDa amino terminus; H_C: 50 kDa carboxy terminal of the heavy chain; H_CC: β-beta tree foil fold heavy chain subdomain; H_CN: β-sheet jelly roll fold heavy chain subdomain; LC: Light chain. Adapted with permission from Montal[17].